In certain defensive missions, placing Snipers in specific elevated positions can cause enemy pathing to break. The Arachnids will often mill around the base of the tower, unable to find a path up, allowing your snipers to wipe out entire waves without taking a scratch of damage.
The most common way to "cheat" within the game's own engine is by using the developer console. starship troopers terran command cheats 2021