A group of game developers called Unreal Software made a 2D version of Counter-Strike.

The game has all the sounds from Counter-Strike itself. The game however is viewed from the top, like in GTA! Cool thing is though, that you can't look through or around walls, so if someone is standing behind a door you are walking through you can see the shape of the room but not the persons in it until you have fully entered in! Now I know this all sounds and looks weird, but the game is fun to play. Next to that this game has a multiplayer section as well, and not only that, you can also add bots!