1. A turret that shoots rockets at a medium distance, same than the rocket launcher
- Why: I was playing deathworld marathon, and I realized that it was difficult to snipe spawners with turret creep. Biters were already blue, and the only things I had was red ammo, grenades and flamethrower. I got poison capsules later, and laser turret allowed me to clear more nests, but it was too difficult to reach spawners because of the distance, not because of worms that are easily cleared with poison capsules, but because blue biters are fast and will quickly surround you.
- How: The rocket launcher has a good range, but a rocket turret would be nice to "snipe" spawners, with the same range of the rocket launcher. To not make it too strong, just make the rocket turret have a low fire rate, and hold a max of 10 or 25 rockets or so.
- Why:The grenade has a very poor range, and cluster grenade is a very late upgrade.
- How: A mortar could have a low fire rate, yet have a decent range to reach spawners. Its damage might be similar with the grenade, and allow the player to slowly kill spawners while hiding behind gun turrets. The mortar is a very common weapon to attack an enemy at a long range.
Also maybe an incendiary grenade?
3. Very late upgrade: make it possible to "mind control" biters, and/or slowly create spawners.
We saw players having fun by encircling biters in a small park like thing.
Maybe add a way to mind control one biter, to create a spawner. This would also be fun to "grow food" in farms or greenhouses to feed biters and make them grow and multiply faster. Of course this would be a very long game upgrade.
