I also play UT (unrealtournament) and the most lasting of the series so far is UT99 and in my case instagib....... but after all these years of playing the same maps over and over again, i have to leave for months at a time as it becomes dead sh1t boring.
Standard vga games are likewise after years and years of playing.
Addons make you think, not only about your race, but also the enemies. If it wasnt for past great sites like spaceport hamburg, and armins penchant for addons and diff ship lists, i may have left vga sometime ago.
What am i getting at,... simple... old skool aint necessarily kool anymore. And Havoks no frills games are pretty much old skool.
"Just because you can do a thing,
Doesn't mean you should."
Paarthurnax the Dragon