In the mid-90s, 3-D first person shooting games were all the rage but Metal Slug stood out from the competition with its simple side-scrolling, two-dimensional action. It was a risk worth taking for Nazca Corporation and SNK who filled their game with cartoony backgrounds and characters to give players plenty to look at (and shoot).

Featuring a joystick and only three buttons--for shooting, jumping and launching grenades--the players guided two soldiers, Marco and Tarma, through a hostile battleground in search of POWs to rescue. The enemy army was numerous and never stopped attacking so the fire button took the most punishment in Metal Slug.

Marco and Tarma fought with standard weapons like knives and guns but power-ups gave them access to flame-throwers, machine guns and rocket launchers. For the really hairy situations, the two commandos fired the Metal Slug itself, a short tank with a mean cannon mounted on top.

Every aspect of the game was tongue-in-cheek, like its definite World War II motif despite the plot taking place in the near future. Enemy soldiers provided some comic relief too, some times running away screaming from a fight or laughing it up when they delivered an especially damaging blow to Marco and Tarma.

Metal Slug spawned many sequels (nothing beats the joy of furiously pressing the fire button), like Metal Slug 2 and Metal Slug X. The follow-up releases introduced new elements into play, from more Metal Slug tanks to armored jets and armored camels. Yes, armored camels, just keep pressing that fire button!