This actually is actually Haze's, but it dropped to the bottom of I&S without being reviewed, which I found was a pity, as it received a large number of positive replies. This is based on his, but with modifications.
Make Turret Factories cost 20 res.
Assume Turret build time is X seconds.
Maximum of 4 turrets can be placed in a TF's drop zone before it turns red.
Drop sentry turret health down from its current 1300 to 750 (10 bites)
Reduce advanced TF cost from 15 to 5.
Commander drops a TF.
Marine builds TF.
TF pre-fabricates free Turret in X+5 seconds.
Commander can now drop a Turret in that TF's drop zone.
Marine builds Turret in X seconds, while new turret begins fabrication in X+5.
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Tourny:
How is it more useful? Turrets are rarely dropped now as a decent turret defence would cost 40 res. Fades come way too fast at 4 minutes for marines to waste res on this. With this, it is only 20 res to build an outpost, but the main trade off the marines must make is time. Waste time to fortify an area? Or press on and be aggressive.
And since turrets die in only 10 bites, 2 skulks can clear an undefended outpost with the loss of only 1 skulk if they focus their bites and alternate damage.
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Pub:
The reason why turrets are so lame in pubs is because you can fortify a hive location from nothing to 10 turrets in 30 seconds. And due to slower alien res flow, aliens usually have little chance of defeating this. At the same time, some teams invest so much into 1 lockdown, they can't afford anything else and are thrashed.
This change helps both ways. A lockdown is now cheaper and frees more res for marines. At the same time, Fort Knox won't be thrown down in 30 seconds, complete with a nursery for the kids while daddy is out fighting the Kharaa. Building a fort takes time, and gives pub aliens a chance to halt a buildup.
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Answering the OMG AUTOMATONS ARE NO FUN school:
Turrets are a part of NS. Yet, the reason why they are loathed, well you guys know that. However, these changes now make turrets useful, as another option, as another choice. However, they are now a strategic consideration, as you have to trade valuable time to fortify an area.
Marines are vulnerable when building. This long build up time will make them easy targets. At the same time, these turrets are nothing like the current adamantium versions being fielded. These turrets can be taken down by plain skulks, easily. No automated defence should stand against players, and these can be.
Turrets are now potential tools for tourny, yet as frail as toothpicks. Time for security. Think about it.