Geo Storm

AKA Gun Force. Gun Force was an obscure Contra-like game you might have seen at the arcades back in the day. It was "feed me all your quarters" hard and pretty much unplayable, but contributed one exciting new element: you could jump into war vehicules and used them against the enemy. Most of you probably didn't even know that it had a sequel. Gun Force 2 was one of the last arcade games (if not the last one) from Irem Corp., published in 1994. When looking at the screenshots, the game's similarity to Metal Slug becomes evident immediately. Yes, Metal Slug is an evolution of this game, as the staff members are actually the same.