Environments are not fluid. Everything looks disconnected, and very little flows well. I see much potential, but at this time, a new engine for Tremulous is a mistake. In fact, I think that at any time, if Tremulous is released officially on a new engine, it will be a mistake (unless, like NS2, it's a COMPLETE revamp and doesn't look like shit). Tremulous doesn't need a change like this. I can play Half Life 2, full settings, and I won't argue that next generation games are amazing looking, but Tremulous can be just as beautifully immersive as any game. (Except Roller Coaster Tycoon 2. Shit, that's fuckin' amazing.)