Garry's Mod: This game is totally awsome, the first day i got it i coulden't stop playing it because it's that fun!
You can just create really anything you can think of, trust me if you have a good Imagination, you can use all of it in Garry's Mod.
It could be used to create comic strips, by posing ragdolls and taking screenshots.
It could be used to create and race cars, by welding objects together and adding wheels and thrusters.
It could be used to create a house by placing furniture and walls carefully around the map and inviting your friends to explore.
Create your own games, or play games created by other users.
So I Recommend You Buying This Game Right Now!
I Have Currently spent 716 Hours playing it, because it's that good.