Few gaming genres are as massively popular as shooter games. Whether it's because of their exciting campaigns or competitive multiplayer, no other genre has come close to replicating the widespread appeal of shooters. However, almost all modern shooters owe their success to a forgotten retro genre.

There's a very clear distinction between 2D and 3D games, but 2.5D games represent the vague middle-ground between them. Although the exact meaning of "2.5D" varies between games, there are a few defining characteristics that set 2.5D games apart from other titles.