Garry's Mod 8.2

The Half Life engine is one of the most robust out there, able to support a ton of different games and genres. While I could list a ton of the most well known games ever that came from this engine, there's nothing that exemplifies its great strength than Garry's Mod.

To install Garry's Mod, make sure you have Steam and Half Life 2 installed. Then follow the readme to install the game.

It's nearly impossible to review this game objectively. This is the ultimate sandbox experience where anything can happen. I've roleplayed as a clone trooper in a Star Wars battalion, expected to learn formations and proper radio etiquette. I've also flown planes to try to bomb a Godzilla that is attacking our city. I've trained to become a ninja and engaged others in ragdoll combat. I've also engaged in gravity gun combat with my friends in a sloppily slapped together junk arena.

There is truly no limit to what this mod can do. The only bad things I can really say about this mod is that its graphics are dated and that there is a substantially steep learning curve to really start learning what you can do with this mod.  Once you get over that, you'll find that there is absolutely nothing else like it out there. 

Garry's Mod is one of the most well known mods for anybody using Steam. If you love games that reward creativity and want to experience some of the most hardcore roleplay servers around, then you should definitely give it a download.