You need a Half:Life Source content. Download content from workshop or internet. Or buy Half:Life Source

If I noticed but thanks anyway. It is the same as in other addons that you need the game to not see it with error.

If you're like me and you didn't understand why it didn't work properly, here's a guide to mounting your game in gmod:
https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=121098599

The main step that I missed is that I did not quit or restart gmod after enabling it, and thereby could not see the models or textures for NPCs.

I am copy-pasting this because there were absolutely zero answers from anyone in any of these discussions on this issue.

引用自 Madiath：

If I noticed but thanks anyway. It is the same as in other addons that you need the game to not see it with error.

引用自 BeeDoodle：

If you're like me and you didn't understand why it didn't work properly, here's a guide to mounting your game in gmod:
https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=121098599

The main step that I missed is that I did not quit or restart gmod after enabling it, and thereby could not see the models or textures for NPCs.

I am copy-pasting this because there were absolutely zero answers from anyone in any of these discussions on this issue.

引用自 Madiath：

If I noticed but thanks anyway. It is the same as in other addons that you need the game to not see it with error.

Thanks , but this happen like 5 years ago... I take free Sven-Coop game in steam and that it.