Counterstrike
The only game EVER to force me to do the following:
Learn and Memorize maps, spawn locations, bomb sites and timings for players running at full speed past specific markers
Play until my fingers literally bled
Play against Bots when no one was around to play against
Buy the first network card I owned
Also the only time in history when someone has told Spartan to "Gooi hom met n landmyn"