Legal to use other game assets in free project?

I am working on a small project that is basically counter strike but only 1 map (using the assets from the game) and some code for the controls and multiplayer but it will have barely any features, it is just really a demo/project for fun but I would like to release it for free so people can try it and play with each other. Would this be illegal?
Thanks.

It sounds like you’re asking whether you can use assets from Counter Strike. We don’t own that game so I can’t comment. But generally speaking, it’s not permitted to use other games’ assets without permission.

This is legal on source engine free mod only. This can be no deal if free and non popular project, for friends only for example, but you can always have problem. Guy who released Half Live 2 before premiere date had ambush organized by Valve and FBI. Luckily he was arrested only be Germany Police and got low sentence if any. If your project is really not popular, well, can be ok. But you can expect troubles anyway. You can use other engines and other non free (public domain) game assets only for closed test, always danger anyway. My 5 cents.

Thanks guys, I might try contacting Valve then and see if they are ok that I use their 3d assets for a educational project that other people can download and see how it is made, I think they should be ok with it because it would never be able to replace the original as it is just a very simple barely working project.