Even though this game is very old, has dated graphics, and more on the expensice scale, it is a blast and can be very I mean very challenging. The game has 50 missions, I am already 2 hours in and only on level 8, that is because I play on harder difficulties. The game contains over 150 weapons, yes a 150! I only have about 25 so far.
The game consists of you killing a alien invasion of giant ants, other insects and ground and flying robots. The vita version has online co-op which works surprisingly well.
If you have questions about it, just reply.