I remember seeing it on the shelves when I went to buy Quake III arena and thinking ""these Epic bozos are copying Id". The main games I played at that time were quake, q2, and half-life. I bought unreal in 98 but could never run it very well (~12 fps, tops) and online *sucked* compared to Quake and later on halflife/CS, so naturally I assumed UT99 would run like shit too, lol!
Well I did get UT during 2000 after i upgraded my PC and graphics. Haha, anybody remember "scimitar"!? That big POS was one of the first maps me and my buddies played all the time lol! I did like all those those huge kitchens, bathrooms, bedrooms ("revenge of the small" anybody?), and loved downtown maps (like zeitkind, zaltag, urban helicopter wars etc). Also remember there were a lot of ghandi maps around online (burgertime, toy wars, frogger, etc) got me playing CTF regularly - i thought he was some kinda mapper god, that was before I started mapping myself - then I saw his maps for what they really were, lol!) I must have downloaded every map that came through Nali City during 2000-2001, lol
I do remember the server browsers at the time (2000-2001) peaked typically around 4000-5000 for both UT99 and Q3... which was a lot compared to nowadays when there's hardly any... Keep things in perspective though - back at that time Half-Life + Counter Srike usually had 50,000-80,000 servers, IIRC, which kinda makes UT99 and even quake3 seem pretty unimportant ...
Here's something I found, which might have been typical in early 2003: