At the beginning it was Quake and Quake 2 then Half Life - but they all were kinda fast paced and not so realistic, surviving a rocket collision always intrigued me. Then Counter Strike appeared, with

"I AM VENGEANCE, I AM THE NIGHT, I AM BATMAN!" Voice acting, characters, story, gameplay - everything is top notch, and the open space map lets you choose the next objective. Also you can play