Charlie "Flayra" Cleveland (flayra@overmind.org) - original author, performs reviews for content accuracy
Karl "XP-Cagey" Patrick (webmaster@xp-cagey.com) - maintains, edits, and presents current versions (send errata to this address)

• 08/17/2005 (v2.2.1) - Bumped NS version to 3.1. Revised Combat upgrade tree and replaced reference to "Pheromones" with "Focus" (oops).
• 02/06/2004 (v2.2.0) - Bumped NS version to 3.0 (formerly referred to as 2.1). Revised entity limit to 275 under the Resource Limits section. Updated the HLTV Overview section to note that overview files aren't used by NS 3.0 and removed related document links. Updated Official Submission Deadlines with latest status and note that source is required from the author for any official map. Added a separate NS:Combat subsection to Required Entities. Updated the picture in The Minimap Sprite to match current minimap style. Updated File Naming Standards with combat map naming standard. Added team_armory to the entity list. Updated team_command entity with new "starts built" flag. Edited note for team_hive. Retitled information added in v2.1.5 as "command char placement", "hive placement", and "starting nozzle placement". Removed indent from paragraphs containing subheader titles. Made spelling and grammar tweaks. Revalidated 4.01 HTML Transitional.
• 11/10/2003 (v2.1.5) - Added Special Locations notes on Command Station placement for bile-bomb, and hive placement, and hive-room resource-node placement. Updated Combat section as gameplay has evolved. Update document version to 2.1.
• 09/28/2003 (v2.1.4) - Added information about including a marine base in Natural Selection: Combat mode, and linked to a .fgd to use for this purpose. Also updated victory conditions. Also updated the submission deadlines page.
• 09/17/2003 (v2.1.3) - Added note about including a hive at the alien start in Natural Selection: Combat mode.
• 09/16/2003 (v2.1.2) - Added Natural Selection: Combat section, detailing map creation for this new gameplay mode.
• 09/09/2003 (v2.1.1) - Added an appendix explaining how to correctly measure the entity limit. Revised the entity limit to 300 under the Resource Limits section. Added "numents" and "entityinfo" to the Console Commands and Cheats section.
• 07/30/2003 (v2.1.0) - Bumped NS version to 2.0 (formerly referred to as 1.1). Removed references to 1.1 and obsolete cheat codes. Added baseline e-poly number to Resource Limits and an appendix explaining how to measure this new limit. Added note about 1.02 changes to info_mapinfo. Added more detailed descriptions of generation parameters for env_particles_custom
• 04/21/2003 (v2.0.6) - Corrected notes for trigger_random. Clarified that changes to info_location are for 1.1 and later. Changed filename guideline for text readme files. Fixed extension errors in sample zip file under File Naming Standards and added ns_yellow.res file to sample zip. Added The .res File under Required Support Files. Added a sample res file to the support files. Removed ns from examples' directory paths in File Naming Standards to remove ambiguity--restated that the ns directory shouldn't appear in zip files as a formal standard (this was already in that section underneath the bulleted list, but is now more explicit). Added a .wav file to sample zip to show location.
• 04/14/2003 (v2.0.5) - Added more notes to info_location,env_gamma, info_player_start, and info_team_start. Updated information in Resource Limits. Changed font for filenames in the text. Changed readme file from a requirement to a recommendation. Noted which cheat commands are going to be removed in 1.1. Changed HLTV doc link to archived copy at valve-erc.com
• 03/23/2003 (v2.0.4) - Added notes to info_location about changes for 1.1. Added Official Submission Deadlines section, linked it to Technical Requirements. Moved File Naming Standards into a separate subsection of technical requirements and rewrote it. Created text readme template for the Required Support Files section.
• 03/16/2003 (v2.0.3) - Fully validated document against HTML 4.01 transitional and CSS 1.0. Tweaked tables and overall spacing, broke up long paragraphs, added horizontal rules to break document flow by topic. Turned minimap notes into full section on Required Support Files.
• 03/13/2003 (v2.0.2) - Grammar and spelling fixes, revised entity guide to match 1.04 settings. Fixed broken links and other known issues. Added building constraints and line of sight back into layout section
• 02/25/2003 (v2.0.1) - Tinted scheme to match marine theme when displayed on screen (printer remains mostly greyscale). Tabulated all entity information. Moved custom particle tool info to a separate document. Planned image layout and added placeholders.
• 02/10/2003 (v2.0.0) - Added a Table of Contents and linked document sections. Refactored content according into technical requirements, style guide, entity specification, and cheat guide. Updated html to use CSS1 and updated broken links. Added clarifying comments to several sections in red text. Updated entity sections to reflect NS v1.0 entities. Updated cheats and commands to reflect full game client.
• 05/14/2002 - Added recommended work process. Updated "performance and style considerations" recommending that mappers use ns.wad.
• 04/06/2002 - Updated performance section (commander r_speeds limit increased, 4MB texture limit stated).
• 03/04/2002 - Added docs for info_gameplay.
• 02/27/2002 - Updated func_resource placement, updated nshulls.txt usage.
• 02/25/2002 - Updated pre-game section. Added second paragraph to "The marine base". Updated the "alien hive rooms" section. Updated the "compile tools" section. Added "Resource model" section. Added "high-detail only" flag to env_custom_particles. Updated func_seethrough notes. Updated creating the minimap section. Updated "Console commands" section. Added env_fog section.
• 12/14/2001 - Added new NSTR2 sections on hive placement, hive room and marine start placement, using gamma, NS hulls, trigger presence and commander mode notes. Removed team_leavegame entity and func_dropship notes. Added flag to info_mapinfo.

This guide will provide you with the information needed to create levels for Natural Selection; it is the official reference for all game specific entities. It also describes the ideas and philosophies needed to make levels that are true to the game's spirit.

Please join the discussion on the NS mapping forum if you have comments or questions regarding anything here. Good luck! The NS Team can't wait to see what you create.

When creating content for Natural Selection, you may occasionally run across references to the NSTR -- the Natural Selection Technology Release. The NSTR was provided to map authors before the official NS mod release to allow them to create content while waiting for the full client. The release of Natural Selection 1.0 made the NSTR obsolete, and the files that the mod installs include everything necessary to create a Natural Selection map.

Before a map can be considered for official status, there are a few technical requirements that must be met. Every alien vs. marine map has a set of entity requirements to allow proper 16 vs. 16 gameplay. In addition, limits have been placed on map resource usage (e.g. texture memory) to allow the game to run smoothly on target systems and required support files and file naming standards have been specified.

Every Natural Selection map must be accompanied by a set of support files that allow it to work properly in the game. See the section on file naming standards for an example zip file layout that includes each of these required files.

The Minimap Sprite - The marine and commander interfaces feature a simplified top-down view of the map that acts as a radar for showing the positions of units. This top-down view is stored as a sprite in the sprites/minimaps directory and should be generated by the map author. To create a minimap sprite, start Natural Selection, enable cheat mode, and type buildminimap in the console. Your machine will lag a bit for a few minutes while a bar at the bottom of the screen displays sprite creation progress. When the process is finished, the sprite will be placed in the directory where it belongs.

The HLTV Overview - Natural Selection 2.0 made use of a full-color map overview for Half-Life TV spectating, but more recent versions have replaced it with a detailed, easy-to-read minimap for spectators. The overview files are no longer necessary.

This is no longer a file requirement for NS maps; this section of the guide has been retained to prevent confusion about whether this requirement still exists.

The .res File - When a Half-Life server downloads custom files to clients, it requires a file named <your bsp name>.res in the maps directory that contains a listing of the files to send. Without this file, any person who hasn't downloaded your map before connecting to the server won't be able to play. Including this file with your map makes life much easier for server admins; they will be more likely to add your map to their server rotation if they don't have to worry about disconnecting clients.

The .res file should contain a plain text list of file names to be downloaded to clients if they don't already have them, with one file name per line. Names should be specified relative to the ns directory (so they look identical to how they are stored in your zip file--see File Naming Standards below). A sample .res file is available here for reference.

The Text Readme - In addition to the files required by the game, it is standard to include a text file in your map's zip file that provides author and backstory information about your map. Many people include an acknowledgements section and compile information as well. For consistency, the file must be named <your bsp name>.txt, and must be located in the maps directory with your BSP file. There is a recommended template for these files located here (right click to save), which can be modified to suit your tastes.

Unlike the other files in this section, inclusion of this file is recommended rather than a strict requirement.

The following standards apply to any map that is seeking official status. All examples are for a map named "Yellow":

• All filenames must be completely lowercase.
• All filenames must be specified relative to the ns directory (don't include the ns directory in your zip paths)
• Your BSP file's name must be in the format ns_<map name>.bsp for an NS mode map (maps/ns_yellow.bsp), or co_<map name>.bsp for a Combat mode map.
• Any custom sprites, models, and sounds must be in directories named after your BSP: (sprites/ns_yellow/mysprite.spr, models/ns_yellow/mymodel.mdl, sounds/ns_sounds/mysound.mp3).
• Any custom textures must be included in the BSP or placed in a wad named after yor BSP: (ns_yellow.wad).
• No file in the standard NS distribution may be overwritten (including setting files such as titles.txt or sounds/materials.txt and standard ns sound, model, or sprite files).
• Naming standards for each type of required support file can be found above.

Your BSP file must be bundled with its support files into a zip file for distribution. Do not create an installer for your map. Include the full directory structure relative to the ns directory (not the half-life directory or any other directory). The zip file should be named after the BSP file (ns_yellow.zip). In the sample case, the contents would be as follows:

• maps/ns_yellow.bsp *
• maps/ns_yellow.res *
• sprites/minimaps/ns_yellow.spr *
• maps/ns_yellow.txt
• ns_yellow.wad
• models/ns_yellow/mymodel.mdl
• sprites/ns_yellow/mysprite.spr
• sounds/ns_yellow/mysound.mp3
• sounds/ns_yellow/myothersound.wav

* - required

The ns_yellow.res file that would be included in this zip is available here for reference.

There are some design philosophies that should be observed to make cohesive maps that work well for Natural Selection. This document assumes that the reader has a basic understanding of NS gameplay (read the About NS page and FAQ at www.natural-selection.org and the FAQ at www.readyroom.org for more information).

It is recommended that maps seeking official status use ns.wad for texturing to maintain a common look to the textures. You may be asked to retexture a submission that uses custom textures before it is accepted as an official map.

Use Web-like Layouts - The alien starting point should be unpredictable, and the three hives should be roughly equidistant from the marine starting location. These requirements, combined with the desired intentional, committal and strategic nature of gameplay, promote a circular, interconnected design. Multiple linear paths leading to each hive from the marine start could also work if the aliens can move from hive to hive without needing to go through the marines.

The desired initial behavior for marine players is advancement in groups while spreading out to find the alien base. The map should create an atmosphere where a minimum of losses are more important than speed; the marine players should spread out to find the aliens' starting point with some urgency, but not at a high resource cost. The marines should have to commit to one or more sections of the map at the beginning of the game; a squad that has chosen one branch of the web should not be able to quickly fall back and regroup with members that chose another path. The aliens should have the ability to cut squads off from each other.

Due to Natural Selection's emphasis on research and scouting, it should take a marine with his default loadout a minimum of 30 seconds to reach the nearest hive, and a minimum of 30 more seconds to travel between any two hives. This spacing should ensure that maps aren't scouted by marine players within the first five minutes of a match, making the game more interesting.

Avoid Level-Over-Level - Natural Selection's commander mode places special limitations on its level designers. The largest restriction is the inability of maps to have rooms over other rooms. If one room is built on top of another, the commander can't give orders in or see into the lower room. Because of this problem, overlapping hallways and areas that cross over other areas should generally be avoided.

This restriction hasn't stopped level designers from creating great maps in other games--Counter-Strike's de_torn doesn't cross over itself but still provides lots of height changes and level-over-level style gameplay. Girders, catwalks, balconies, pipes, and other smaller areas can cross over each other to provide level-over-level gameplay as long as they don't block commander access to the area below them.

Although the commander's viewpoint is always from the same height (specified in the map's info_mapinfo), level designers can use height changes to keep the map interesting. Ramps, pits, and elevator shafts can all be used so long as r_speeds remain under the specified limits and the commander can select players easily in all areas for giving orders.

Create Choke Points - There should be one or more good choke points between the marine starting point and each hive room enabling the marines to build a safe area and have logical locations for deploying siege weaponry and phase gates. Ideally, there should be at least one marine-accessible location outside each hive room that can be used to attack the hive--the marines shouldn't have to run into the final room and engage the aliens in close combat on their turf.

The marines should have the opportunity to fortify an attack point by welding vulnerable openings shut and deploying siege cannons with marines on defense. The aliens should prevent this from happening by evolving to anti-siege forms.

Between choke points there should be relatively safe areas where marines can cover each other and leapfrog forward, interconnected by narrower, more dangerous passageways. The level should promote organized marine movements by squad with players advancing and covering each other.

Determine Line of Sight - Natural Selection computes line of sight for the commander based on the other marines' line of sight. A commander scrolling over an area will only be able to see enemies and enemy structures visible to his teammates:

The commander looks down at an area where a hive might be while his squad pauses behind a large door nearby. The commander sees only an empty room until one of the marines opens the door, revealing a hive to his squad--the hive then pops into view for the commander, too.

The effect is the same for both enemy players and enemy structures. Sounds and weapon effects are still played for the commander normally; the commander can deduce information about an area that he can't see using these hints. If he's hovering over a ventilation shaft with a noisy alien inside, he'll be able to hear the alien if he's close enough. If the alien fires a weapon, the commander will see his weapon effect, but not the alien itself. The commander can also use a scanner sweep to reveal areas outside of the team's line of sight for a few seconds if the team has built an observatory.

Constrain Buildable Areas - Marine commanders and alien builders both have limitations on where they can place buildings. These limitations allow mappers to decide exactly where each team should be able to fortify their positions.

Avoid Outdoor Spaces - Natural Selection gameplay is balanced for interior environments and small spaces. In an open air map, flying and crawling aliens pose special problems that don't have a clear solution. If outdoor areas are used in a map, some explanation must be given why boundaries exist on the sky (these boundaries should not be invisible, and they should not be a texture that crawling aliens can wall-walk on. A map can have exterior views without causing these problems, and solutions like biodomes are recommended (but not encouraged) over open-air environments.

Create Alien Only Paths - The basic layout should include areas where the aliens can take alternate paths not accessible to marines. Try to make areas that accommodate and promote the various alien movement types (wall-running, gliding, flying, leaping, and blinking) and reward skilled alien players with routes that are difficult but not impossible to take by using these methods. Ventilation shafts, electrical tunnels, and power conduits should allow aliens to ambush and flank vulnerable marines. These alien only routes should connect the alien hive rooms with each other and allow aliens to travel between adjacent web branches. They shouldn't be overdone; the marines must be able to understand which openings should be watched or blocked off if they want to fortify an area. There can be occasional hidden openings, but most entrances and exits from alien paths should be obvious--gratings, still fans, holes, and access tunnels. The aliens should be encouraged to use areas accessible to marines about half the time. Making tunnels more difficult to access or longer than the regular hallways can help to encourage this behavior. There should also be shortcuts through the map available to marines with jetpacks that have advantages over normal routes, rewarding the commander for research on jetpack technology.

Direct Onos Movement - The largest alien has a bounding box that measures 64x64x108 units. Because they are almost double the size of other players, these aliens require special consideration when constructing levels. Make a few wide hallways near the alien hives so an Onos doesn't have trouble defending, and connect the hives and marine start with at least one Onos-friendly path. Making smaller hallways that aren't accessible by large aliens can help balance choke points.

Include Welding Points - The aliens' advantages come from their evolution into forms that have better adapted to the environment. The marines' advantages stem from adapting their environment to themselves. Marines should have the ability to protect and fortify choke points and cut off secondary routes through the level with their welders. The func_weldable entity can allow marines to open or close off new areas of the level. Some care is required to balance the welder with the alien's movement advantages.

Plan for Commander Interaction - The marine commander has access to the ship or station electronics, which allow him to "jack into" his location, performing diagnostics and light repairs. As a result, the commander can operate any "useable" door, lift, switch or other entity. If he clicks on it, the entity is "used", exactly as if a switch was thrown from the ground. The way the game determines this is by running through all the entities in the level, and marking all the "useable" entities and their targets. Any "marked" entity can be used by the commander. For example, if a button opens a door, the commander could click the button or the door to open or close it. Note that generally, map-makers won't have to do anything extra to activate "hacker mode", it will just happen automatically. It's not currently possible for a map-maker to make a door that is only activateable by players on the ground (for instance, a door that requires two buttons to be pressed at the same time to be opened). A special naming scheme could be added to prevent the commander from using a certain entity. In this case, the entity should show the reason why the entity isn't linked up to the ship network, via sparking cables or an open control box.

Promote Player Coordination - Natural Selection attempts to have memorable and cinematic games that strengthen the bonds between players. Games where you say, "Remember when you punched the elevator button and backed away and as it slowly opened we saw the elevator was FULL already and turned to run....". One way to accomplish this is to have sections of the map which cause a group of players to pause and look in the same direction, or to wait for another player to do something--events that cause players to realize that, for a moment, that they're all doing the same thing.

The marines in particular should be watching each other often. Create areas wide enough for multiple players to walk, fly or scuttle through at once, or a quadruple-wide ladder that multiple players can use. Create somewhat noisy freight elevators, loading bays, and doors that can only be opened by having two buttons being pressed by two players at once. Use clocks that show when an event is going to happen--anything that helps players recognize the effects of others' actions or makes one player dependent on another. These cooperative elements are more important for the marine players, as alien players generally will lead coordinated but separate attacks.

Tasks that require two players could potentially be performed by the commander and a single marine.

Create and Name Landmarks - Creating areas with a distinctive theme makes it easy to describe parts of the map during or after the game, simplifying coordination by both sides. Landmarks and player coordination (above) promote interaction between teams and teammates, making the games more enjoyable and memorable. Try to add at least a few of these elements per map, especially around choke points. Use the info_location entity to name landmarks.

Add Gameplay Related Sounds - Gameplay related sounds help players to understand and react appropriately to the environment. If the marines hear a bay door opening and they're all in line-of-sight, they will know the aliens have breached the area and can react. If the aliens listen for a tram to start up, they can visualize where the marines are and try to track them (or the marines can outwit them by hitting the button and then not using it).

Depict Alien Infestation - The map's look and feel should gradually change between the marine and alien starting points, becoming more "alien" as players move closer to the hives. This continuum will really help players know where they are, and get them to feel the tension they should as they leave their territory. Choose an artistic style for each side, for example:

• Make it as though the jungle-like aliens have somehow transformed their areas of the ship into their natural habitats from their homeworld. A flooded boiler room could be decorated with draped cables and floating debris to simulate a "bog". A hive room could have treelike structures with connecting "branches", formed by fallen transmitters and posts.
• Make the marine base completely dry with some dripping water nearby; add puddles of standing water close to the hive rooms with the hive rooms be flooded with waist deep water.
• Make the marine side "dead" and the alien parts "living"; keep the marine side quiet (good for marines to hear the alien growls and squeals) then create a massive fan room and generators that drone out voice communication and scare the marines as they get farther away. Have little "ambient movement" on the marine side, then have moving fans, malfunctioning elevators and unexpected gusts of steam erupting from pipes as the marines get closer.
• Consider choosing two drastically different colors or lighting schemes and slowly morphing between them as the players travel from one area to the other. Use only ambient lighting and lights coming from fixtures on the marine side, shifting to only ominous texture lights towards the aliens. Try making the marine side technological and controlled, the alien side organic and primal, then see how slowly you can transition between the two.

Use High Contrast Lighting - Strive to make the lighting feel dark without being dark. A near-dark corner or two is fine, but never make areas that are completely dark. This promotes replay and reduces general frustration. Use high contrast areas to promote a feeling of darkness. The env_gamma entity can increase the contrast of otherwise washed out maps.

Add Inaccessible Details - Creating small, detailed areas that can be viewed but not entered is a great way to create powerful custom effects. Create a little side-passage with a half of a broken electrical door showing exposed wires, puddles and blinking lights behind it. Create wire gratings that only partly conceal a detailed mess of pipes and and wheels. A hole in an elevator shaft that reveals a cafeteria that's now a grotto. A crack in the wall that shows a hollowed out area filled with cables. Crinity is the true master of this and it makes a huge difference in enhancing the ambiance of and creating wonder in his maps.

Avoid Terror and Gore - Natural Selection is about lush, atmospheric sci-fi environments, cooperative strategy, and intense battles. It isn't about scaring the player or horrific environments. The aliens will still be scary, but very dark environments, flickering florescent lights, bodies slumped on rafters, and other staples of the horror genre don't help Natural Selection achieve its goals. Don't place dead colonists anywhere (slumped against walls, in piles, etc.). Pools of blood and dismemberment are also to be avoided. The game doesn't avoid blood and gore completely, but doesn't display lingering dead bodies and gibbed alien flesh. In fact, NS is less gory than Half-Life. This may seem like a senseless guideline, but it will help the game appeal to more people--hopefully resulting in more players, more add-ons, and a broader community.

This specification is meant to bring knowledgeable Half-Life mappers up to speed with mod-specific changes made for NS. If you are looking for a specification of general Half-Life entities, try the Valve Editing Resource Center.

To use cheats, the console variable sv_cheats must be set to 1. If sv_cheats is 0, the console will respond with "unrecognized command", even though it IS a recognized command. When cheats are enabled the game will start when any team has one or more players and the round will never end.

Console commands listed here are NS specific. Additional Half-Life testing commands and cheats can be found elsewhere.

• In-Game Tools
  • setculldistance # - used to find the minimum culling distance needed for commander mode.
  • setgamma # - sets the current env_gamma level, where x is a number from 1.0 to 2.0. This affects all players.
    
  • toggleeditps - displays particle editing interface
  • editps <name> - selects particle system to edit
  • listps - lists all particle systems in NS and in the map
  • buildminimap - generates a new minimap. Very CPU intensive. Saved in the ns/sprites/minimaps directory.
  • numents - lists the number of runtime entities on the map
  • entityinfo - lists runtime entity counts by type
• Game Event Commands
  • startgame - starts game immediately (untested for a while)
  • endgame (#) - ends the current game (as a victory for team #, defaulting to team 1).
  • tooltip <name> - adds a tooltip named <name>. It will translate this tooltip from titles.txt if found.
  • givepoints - gives you some points
  • testevent - plays a "you just got points for killing the enemy" event
  • alert - generates a random alert.
  • deathmessage <weaponname> - sends test death message to all, e.g. "deathmessage machinegun", "deathmessage bitegun"
• General Map Testing Cheats & Commands
  • jointeamone - causes player to join team 1
  • jointeamtwo - causes player to join team 2
  • spectate - causes player to join spectators
  • autoassign - automatically assigns the player to a team
  • getnumplayers - Reports the current number of players
  • killall - Kills all players in the game with your current weapon (won't kill teammates unless FF is on via tournament mode)
  • invul - Toggles invulnerability for self.
  • highdamage - All damage is x100 vs. buildings, x10 vs. players
  • slowresearch - Research takes full time instead of normal 2 seconds when cheats are enabled
  • detectall - for testing motion tracking and marine blips
• Alien Map Testing Cheats
  • spawnhive - If alien, adds a new random hive for your team
  • killhive - If alien, removes a random hive
  • addcat # - Adds an upgrade category, as if you had built an upgrade chamber
    1. defense
    2. offense (no longer used)
    3. movement
    4. sensory
  • removecat # - Opposite of addcat.
  • redeem - Makes it easier to test redemption
• Marine Map Testing Cheats
  • startcommandermode - Teleports to the first command station it finds and starts commander mode. This will sometimes teleport you inside geometry.
  • stopcommandermode - Drops out of command mode
  • bigdig - Buildings are built instantly when placed
  • hightech - Research happens almost instantly
  • orderself - Gives your commands to yourself so you can logout and see how they look on the HUD. There's no way to stop doing this after you've started.
  • killcs - Kills all command stations.
  • setskin x - Sets the player's skin (0 for white marine, 1 for black marine)

Most of the resource limits specified in this document are self-explanatory but the "baseline e-poly" value requires clarification. The value that the Guidelines give (2100 polys) should not be compared to the r_speeds number during map testing. The e-poly number displayed by r_speeds is an indication of how many model polygons (loaded from mdl files) are currently being rendered on the screen. The mapper has no control over how high this number can go during a game because it includes polygons from any buildings, players, and equipment on the screen.

Instead of attempting to limit the total e-polys on the screen at once, the guidelines set a limit on the number of model polygons that the mapper can place in any one area. By limiting the mapper's contribution to e-polys (the "baseline" value), the Guidelines are attempting to keep the total value low while still giving the mapper some flexibility. Any custom map model polygons in a scene count toward this limit. The worst-case number of polygons caused by the following entities are also counted: team_command, team_hive, and func_resource. These numbers are given in the table on the right. The player's weapon and any models spawned during the game (e.g. dropped weapons) don't count towards the limit.

If you don't place any custom models in your map, you don't have to worry about this limit if you stick to the following maximums: no more than 1 hive viewable at once, no more than 2 nodes viewable with a command chair, no more than 1 node viewable with a hive, and no more than 3 nodes viewable at the same time from any angle. Don't count command chairs placed by commanders in the limits.

The guidelines limit the runtime entity count for a map, but this number isn't the same as the entity count displayed by an editor. The following entities that are removed when the map loads can be ignored for the purposes of this limit:

• info_player_start
• info_team_start
• info_location
• info_null
• light without any "targetname" (Name in Hammer's object dialog)
• light_spot without any "targetname"

There are two developer commands that mappers can use to assist in staying under the runtime entity limit: "numents" and "entityinfo". "numents" displays the current runtime entity count--running this after a map as first loaded will give the number to use for comparason to the limit. "entityinfo" displays a listing of loaded entity types with the detected count of each; mappers can use this command to find out what types of entities are contributing most heavily to the total count to help them optimize.

This appendix details the creation of an alternate gameplay mode of Natural Selection. NS: Combat is a simple, combat-focused version of NS without any resources, structures, or commander. It isn't meant to replace standard NS gameplay, but has been designed to be a "starter" mode to introduce NS concepts more gently. Since it is less complex, NS: Combat will also allow small groups of people to play together (ie, at a cyber cafe, at the office or home, etc.). NS: Combat is slated for inclusion in NS 2.1.

NS: Combat is a simpler, easier-to-learn, smaller scale combat experience that introduces players to the technology and weapons of Natural Selection. Players start as marines or skulks in short timed games. As players kill enemies, they gain experience toward "levels" that allow them to choose from better weapons and armor, improved abilities, tech upgrades, or evolutions to higher lifeforms. Players start at level 1, and can earn up to 9 additional levels.

Death and Respawn - Dead players respawn in "waves". Whenever a player dies, a respawn timer is started. When the timer expires, all dead players immediately respawn at their base without losing any levels. Additional deaths that occur when the timer is active do not cause it to reset, but if all the players on a team are dead at the same time, that team immediately loses.

Scoring - The scoreboard shows every player's current level and number of kills. Team scores are the sum of team member levels.

Winning Conditions - If the marine team destroys the alien hive, they win. If the aliens destroy the marine command chair, they win.

When a player gains a level, a menu allows them to choose which improvement, upgrade or new equipment they want. Marines can change their weapon type, get an equipment upgrade (e.g. weapon upgrades), upgrade their armor type, or resupply ammo or health to themselves and nearby friendly players. Aliens can unlock the next level of alien abilities (normally linked to hives), purchase a level 3 upgrade, or evolve to a higher lifeform.

Maps for NS: Combat are simpler than regular NS maps, and have slightly different entity and design requirements. Unless stated in otherwise this section, all mapping guidelines in this document apply normally to Combat maps. Please submit Combat maps to the NS team as you would a normal NS map.

• Make sure you have the latest .fgd which will allow you to place structures in your map.
• Combat maps should be named with a "co_" prefix, instead of a standard "ns_" prefix. This prefix tells NS that it's a Combat gameplay map. Examples: "co_hera", "co_eclipse", etc.
• Place one team_command, one team_hive, and one team_armory in the map, but no func_resource
• Create a standard ready room and team join portals.
• Place 16 info_team_start entities for each team. The aliens start at the only available hive in this mode.
• The overall size of Combat maps should be smaller then the average NS map, roughly matching the size and complexity of Counter-Strike maps. Combat maps should play well for small groups (1v1, 2v2, etc.).
• Maps should have fluid, DM-like connectivity to promote intense combat and movement.
• Concentrate on making maps as simple as possible while providing strategic depth. Since Commander Mode isn't used in NS: Combat, level-over-level play is encouraged!