most popular linux game engine?

Answer 1

Im very glad to see you ask this. We presently have more engines than we do games. :(

Unfortunately I dont feel qualified to answer it since I have not tried multiple game engines. I tended to skip over engines and looked at MUDs, Quake server, Ultima Online server, World of Warcraft server, and Dominions 3 server (my favorite)

Here is a good site to visit. And I wish you good luck.
http://www.devmaster.net/engines/