Introduction and questions.

So, i’ve played every sandbox ever made. Maybe missed a few oldies, but besides that, ive played and beaten them all. Just recently beat L.A. Noire, and sadly it has no potential after the story is done. So i’ve been looking for a new sandbox game.
After searching through a couple of forums I kept seeing GMOD pop up as a great sandbox. Went to the website, saw it was a sandbox with no goals, just do whatever you want. So i’m excited. But confused.
It says I have to buy either counter strike or team fortress 2. Why?
Is this not a game itself?
And what exactly is there to do in this game. I’m very confused on the concept of GMOD. Any explanations are greatly appreciated.

You build shit.
Pretty much the main idea.
Anything you want to. From aeroplanes to cars to wire turrets and funky buildings. MAKE ANYTHING YOU WANT PRETTY MUCH.

Okay so, what game do I download? Counter strike? Team Fortress 2? Half life? Portal?
What is the best source game for gmod. In terms of graphics and everything else.

I’d go with Counter Strike Source, since most servers uses content from it. Skyboxes and weapons are usually CSS, so you should go with it. Eventually you should get Team Fortress 2, because it has a bunch of great maps, models etc. But if you just want to get the best gaming expirience right now, go with Counter Strike Source. . . oh and remember to also play the games, they’re beast!

Your choice of game does not impact the graphics in gmod, it uses the most up-to-date engine, everything included. The reason why you have to buy an other source game is because gmod does not include a license for the source engine (you may not realise it, but when you buy a game, you are not just buying the contents of that specific game, you are also buying a license to use the engine that the game uses to run it).

Gmod can use the content from almost all source games, but you need to own the game to use it (the process of importing content is handled automatically on starup). Gmod always comes with the props from half-life 2, whether you’ve bought it or not. If you only play single player you don’t really need any extra content from other games, since everything good, fun and useful that you will ever need can be downloaded as mods made by the community, completely free and legal.

If you, however, are going to play on servers, in the vast range of gametypes that have been created by the community, you may need to purchase some extra content. You are by no means forced to, as any missing models will be replaced by a big red error model and missing textures will be replaced by pink-black chessboard-style textures. It doesn’t necessarily impact gameplay, but it looks awful.

Since you probably don’t know now how you will play yet, I agree that you should buy CS:S. Most servers use a combination of hl2 and css content, and since the hl2 content is free you will have a mostly error-free online experience that way. If you, however feel like spending money, you can always get the valve complete pack. That way you get nearly everything possible.

You build, you create games, you create maps, you code with lua.

You should buy Half-Life DEATHMATCH and Counter Strike: Source. Those are commonly used.

Check out something called Trouble in Terrorist Town, or just Fretta in general.

When you first start off just play around in single player and try every single feature. The more you go to servers the more maps you will collect, or you can manualy download them. Make sure to download wire mod.