Garry's Mod has no real purpose other than letting you have fun messing with game objects; there's no true "game" here (although if you're crafty you could use it to code up your own online multiplayer game).
A very cool feature is the ability to import enemy NPCs from Half-Life 2, allowing you to either fight them yourself, or stage massive NPC versus NPC battles.
|Combine soldiers battle a swarm of Antlions|
As you can probably imagine, this has opened the door for amateur filmmakers to utilize stop motion techniques to create their own short videos, usually starring Team Fortress 2 characters. Who can forget such timeless classics as Sniper is Stupid?
Top notch animation right? That really puts Pixar to shame doesn't it? To be fair though, I have seen a few Gmod videos with incredible stop motion animation constructed out of thousands of screenshots.
Now you may have noticed earlier I said that Garry's Mod allows you to manipulate the facial expressions of the character models. This is where the strange factor comes in. In addition to standard models that allow a limited range of facial expression, the game contains an additional set of models where you have full control of the faces, which can lead to some unexpectedly terrifying results:
And because Youtube is.....Youtube, there are people willing to take these horrifying facial expressions to the extreme (I apologize for any IQ points lost during the viewing of all these vids).
Okay, I feel like this is enough brain-draining stupidity for one blog post. If for some reason you can't get enough, by all means head over to Youtube and continue the search (a good starting point is typing something involving a TF2 character into the search box, such as "Heavy is ").
Thanks to the free release of Valve's Source Filmmaker software, which includes tools for creating smooth animations (no need for stop motion here), there has been a steady decline of Gmod videos being produced and shared.
If you're a huge fan of Valve's games, or just sandbox games in general, you should head over to Steam and check out Garry's Mod ASAP, because it really doesn't get much better than this. One last thing I should mention is that Gmod contains a huge database of free downloadable characters/props/maps (my personal favorite is the Kakariko Village map from Zelda: Ocarina of Time). Have fun, and if you decide to create a masterpiece of stop motion animation, be sure to send me a link because I'd love to see it!