Putting it short, Garry’s Mod runs Valve Games, but isn’t owned by VALVE. They should start joining and you’ll be able to play together!.Have your friend open their overlay and click the invite.Right-click the friend you want to invite, and click “Invite to Game”.Click “View all friends” at the middle-left.Open the overlay by holding SHIFT and hitting TAB.Find one you and your friends can all join and play together. Click on ” Play Multiplayer” to bring up a listing of all available ” GMod ” servers. Load ” GMod ” to access the game’s main menu. In order to play ” GMod ” with your friends, you will need to either create a server or join an already existing server. 6 How do you go into 3rd person in Garry’s Mod?.1 How do I play Garry’s Mod with friends?.