X-Morph: Defense

While its storyline certainly leaves some things to be desired in the campaign mode the gameplay is pretty solid.

Hard difficulty requires a huge deal of on-the-spot adaptibility, sometimes requiring you to lose a wave in order to see how everything spawns in so you know what to kill first, what you need to run the longest path for, etc.

Plot is good, but everything else you got is just old soldier grumbling.

Playing the same level in coop suddenly becomes quite easy, because you have twice the amount of towers.

You can blow up bridges, clear out trees and basically cause absolute mayhem while spanning your high tech laser / flame / rocket / plasma towers all over the map, not even speaking of the laser fences, all of which looks really great thanks to the nice artstyle and visuals.

Very good challenge level on Hard and Brutal difficulties, requiring both combat skill and strategy to win.