(See 'Downloading' at the bottom of your steam client.).Click '+ Subscribe to all.' / Let anything downloading in Steam finish.(If you're having trouble opening console when you launch Gmod, open settings first then hit ~.

Open console, paste and enter/run the command without the quotes: 'menu_cleanupgmas' / Let it finish.

(Check the very bottom for last resort options.) If your game displays this message regarding the map try just unsubscribing and resubscribing to THIS MAP ADDON. If not you may want to look into running those games or reinstalling them with gmod to try to get them to associate with each other. Garry’s Mod (GMod, Garrysmod) is a sandbox physics game created by Garry Newman, and is built on the Source engine. It will show an X no matter what if you're using a texture pack and that's fine usually, but if you have the games installed they should show up checked. Garry’s Mod requires the user to own at least one Source engine game, such as Half-Life 2, Counter-Strike: Source, or Day of Defeat: Source, in order to play. Anything that requires a 'Source' for Gmod basically means you have to the buy the game linked with it. Also while we're at it, check the little controller icon at the bottom right of Gmod's title screen to ensure 'Counter-Strike Source' shows a check mark and not an X by it.

i.e Team Fortress 2 Source requires you to have Team Fortress 2. This is a tutorial to download and install css for gmod, no lag no errors no more checkerboard crap.Download: (old). Just keep in mind which games are compatible with Gmod. You need to buy Counter-Strike: Source, there's no legal workaround.

Gmod css textures steam workshop