darkplaces?
Heh, no fooling you Empezar.
First guess too. Others were guessing things like Tremor, QMB and Qrack.
I was messing around with it the other day and wanted to see if I could make it look more like engines I like to use.
Truth be told, like I suspect many other multiplayer types felt, I didn't view DarkPlaces as a serious engine for DM purposes. But that changed last week when I got some assistance in finding some really outstanding settings.
I've given it some tests on both NetQuake and QW servers (it does support connecting to QW servers now) and get the most responsive mouse and FPS smoothness I've seen in a client. As a result it has some really sweet aim and the shaft is one of the best in any engine. (This is the latest beta build, dated late May 2006 or so).
For players like myself that play more NetQuake than Quakeworld, I find the look of QW prediction and the accompanying animation awkward and using cl_movement 0 I get a very NetQuake feel on QuakeWorld servers, a QW player should use cl_movement 1 since they are used to that.
I would add that the support to connecting to QW servers is not perfect, but I've played several games on QW servers with it. I've had trouble in some circumstances, and DarkPlaces does not have all the things that someone expects (impulse 8 2 1, record demo when connected, loc support -- to name a couple of key ones).
But I've found taking a look at DarkPlaces again to be very interesting, especially since it now has PNG texture support (I personally feel that TGA is a 1990's format and reject TGA because it is not an internet friendly format for displaying textures).
Anywho ... I'll post some settings later for anyone who wants to play around with it. Without the above features it isn't really handy for serious play, but should be useful for FFA like at, say, XS4ALL or casual play. Definitely worth a look for someone who hasn't tried it lately.