That has an open source engine but everything else isn't open source? Like the models, sound/music, textures etc.?
For instance, taking the Ogre engine, making a game and then sell it, or because it's open source you aren't allowed?

Just a general question.

you can even sell vim if you find someone willing to pay for it.

in the case of mixed licenseing there are some packaging rules iirc, eg you should not have the closed and open content "in the same zip". other then that you can use oss parts in a commercial project afaik.

The issue is not relating to the source status; the issue is any restrictive clauses in the licensing.

It is permissible for GPL v2 software to be sold, with propriety software & for a proprietary platform, however it may not link with proprietary software; LGPL exists for that purpose.

I'll sell you a copy of Nexuiz if you like , the funds would go to Alientrap of course