The core of GMod is building. You can start by spawning basic props and "welding" them together using the to create cars, rockets, or even complex robots.
While the single-player sandbox is great for learning, the game truly shines in multiplayer and with community mods: Guide :: Gmod: How to have fun - Steam Community Garryho mod
: Hold Q to open the menu where you can spawn props, NPCs, and weapons. The core of GMod is building
Garry's Mod (GMod) is a creative sandbox game where you can manipulate objects, build contraptions, and explore countless community-made game modes. Because it is based on the Source engine, many of its mechanics will feel familiar if you have played games like Half-Life 2 or Counter-Strike . Essential Controls Garry's Mod (GMod) is a creative sandbox game
: This is used for advanced building (e.g., welding, creating thrusters). Select a tool from the right-hand side of the Spawn Menu, then Left Click on objects to apply it.
: Press V to fly and move through solid objects, which is essential for building and fast travel.
: Use WASD to move, Space to jump, and Shift to sprint.