Okay! Counter-Strike, if you're not a gamer, is an immensely popular multiplayer modification to Half-Life and Half-Life 2. Two teams, terrorists and counter-terrorists, face off on a map, their goals being to either kill all the members of the opposing team or prevent them from completing their objectives, which vary depending on which map is being played.|
It's an incredibly fun game, highly addictive, and the most popular first-person shooter in history (according to Wikipedia, Counter-Strike servers produce more internet traffic than the entire country of Italy). Of course, it's not without its problems. The CS community has a reputation for being a bit... juvenile. There's also a lot of hopping around, mainly to throw off the aim of the inevitable crowd of unmoving snipers.
Posing Notes: I'm not great with Photoshop, so it's nice that Garry's Mod includes a number of effects you can add right there in the game, as seen in Panel 2.