You can post your game "concept" (videos, screens, idea) on steam greenlight, then maybe someday your game will be available on steam, if it pass greenlight. The greenlight procedure costs US$100.- , you can find more info about greenlight on steam.
You can also sell it everywhere else, where you want.
Royalty free means, after you've bought GG on steam, you've to pay 0,00 to TGC when you release and sell your game.
Old school FPS fan, DOOM!!! Why GG not working on my AMIGA 500?
