[cPhoenix]

What if, someone were to make a new game.
Which can only be installed if you own a copy of counter-strike1.6.
This game itself doesn't modify any files, use any DLL but only textures and models.
The game's dll's and its extra resources would sit on the separate folder. ( where cstrike, valve etc... folders are. )

I don't think it can be even consider a mod but would something like that be legal?
Considering that this project would aim for profit. whether directly from purchase or indirectly from micro transactions.

[bigdaddy424]

Similar to Counter-Strike: Online and Nexon Zombie, but Valve takes a cut on %.

[VXTech]

Originally Posted by cPhoenix I don't think it can be even consider a mod but would something like that be legal?

I have found a thread that can be the exact answer to your question. Hope it will help you

https://forums.alliedmods.net/showthread.php?t=339013