Finding a Multiplayer Game
The Multiplayer aspect of Garry's Mod is most likely it's biggest and best feature. With literally hundreds of community servers and gamemodes, and even more players, it's difficult to not find something new.
As an obvious disclaimer, multiplayer experience will vary. The quality of servers will widely vary.
Finding a Multiplayer Game
To join an active Multiplayer, start at the Main Menu. From here, select the "Find Multiplayer Game" button.
The Multiplayer Menu
Selecting this option opens the multiplayer menu.
To the left, you will see the different options available for browsing Multiplayer servers.
Unlike the older server browser, which simply showed all available servers, the newer browser groups servers by gamemode.
To the right, you will see the gamemodes that are currently available to join.
Internet will show all online gamemodes available.
Local Network will show all gamemodes available locally ("LAN").
History will show any servers that you have previously played.
Favorites will show any servers that you have added to your favorites list.
Refresh Listings will refresh the gamemode and server lists.
Legacy Browser will bring up the original server browser.
Using the Server Browser
To start, chose a gamemode that you would like to play. Gamemodes are sorted by how many players are currently in that game. Select your chosen gamemode. You can return to the gamemode menu by pressing the blue "Return to gamemodes" button.
After choosing your gamemode, you will continue to the Server List.
By default, servers are ordered by their Ranking, as seen on the far right of the server list. Servers are ranked by multiple variables such as ping, players in the server, and if you have the current map or not. Ranking is intended to help you find the best server possible.
Along with ranking, servers can also be ordered by Name, the current Map, the number of Players currently on the server, and the servers Ping.
It's also possible to search for servers. Simply enter your search terms in the box in the top-right of the server list. It will search server and map names.
Choose the server you want to play on. I recommend choosing the server that has the highest rank. Click on the server you want to join.
After clicking on the server you want to join, the Server Menu will appear to the right. This menu contains useful information such as the name of the server, the server's IP address, as well as a list of players, showing their names, game score, and time spent on the server.
To join a server, simply click the blue "Join Server" button on the server menu. You will connect to the server, and download any necessary files.