Starship Troopers (2005) [cheats]
Start the game with the -devuser command line parameter. Then press ~ during game play to display the console window. Type help as a console command to display all the cheat codes. Enter one of those codes at the console window to activate the corresponding cheat function.
Royal Guard/X-Bug Weakness
The Royal Guard bug and the X-Bug both have similar weaknesses in that they are invincible everywhere except for their red eyes. For the Royal Guard bug, simply shooting out both eyes is just enough to expose the vulnerable nerve stem for your weapons to kill it.
The X-Bug makes this harder by forcing you to shoot the nerve stem to provoke it into rearing up. This exposes its yellow weak spot underneath. You only have two whole seconds to spray it before you have to expend a ton of ammo on the nerve stem to make it rear up once more.