If you like little shooting orgys, you may like XEvil. The aim of the game is to kill the other units. This is "contributed" by graphic and by sound (that's why it is for people older than 16 yrs).
The graphic isn't very impressive (only 256 colors). But therefore the game has much of options for making the game like you wish to be. So you can change to "Kill-Kill"-Mode if the Level-Mode is kind of boring to you. You can collect up to 13 different weapons and 10 powerups. The weapon range is from the normal pistol up to the flamethrower ;D. For the perfect control about your fighter, it may be necessary to study the instruction.html.