You start the first level with only a pistol with sixty rounds and 3 bombs, you can pick up other weapons from item bins randomly littered throughout the stage or pick them up off of dead enemies (same goes for health items) its relatively hard to aim in the game but it fortunately doesn't take much to kill most enemies in the game, it being usually around a shot or two.
The other mode in the game is the arena mode, in this mode you first pick one weapon set of the nine available giving the user a variation of play style choices and then has you fight against a set wave of specific enemies in a set environment but randomized level until you can make your way through all 4 environments trying for your best score