The things that drew me to Tremulous were more to do with the project, it's philosophy and it's community than the game itself. To be honest I spend more time modding games than actually playing them.
I ended up on these forums because I was interested in working with a GPL game engine. I did a bit of shopping around and decided that the quake3/ioquake3 engine was the one that interested me most (at least until Doom3 is GPLd). I then started looking at games that ran on quake3 derived engines that had a good user community. The three main contenders were tremulous, openarena and urban terror, so I spent some time reading the 3 forums of each. Openarena was an interesting project with a strong GPL policy, but the project was run by a single person with too much power, instead of more democratic team of devs. Urban terror had some nice points, especially their collection of textures, but their aggresively anti-modding attitude and ultra-restrictive license ruled it out for me.
Tremulous seemed like the healthiest option. It was run by a team of devs who seemed, from what I read of their posts, to be pretty reasonable people. The forum is a friendly place, with a good amount of helpful, knowledgable people. Modding is an accepted part of the culture and the media license is pretty unrestrictive. This convinced me that Tremulous was the right game for me.
