Doom 2

Doom 2, or Doom Reloaded, is your classic Doom game from the nineties. Use the arrow keys to move around the X button to shoot. The space bar has you interact with other objects (like opening doors) and Q, A, and W help you look around while standing still. The object is to kill your enemies before they kill you, pick up better and badder weapons to make that job easier, and grab key cards to let you out of the rooms and levels. This game was popular for a reason - the maps get more and more intricate as the levels progress, the weapons are fun to fire, and bad guys are creepy aliens. One of the best FPS ever!