I agree with TheAgent, I would love to play UT99 on UE3. But I would love it even more if Epic did an HD Remake on UE4.
Either way, I hope that Epic includes the ChaosUT mod stuff as part of the new UT'99 if they do it. Exploding crossbow bolts, RPB (explosive) sniper rounds, and a Gothic (in the subculture sense) Bastard Sword FTW.
I also got a kick out of these guys, though they can be very frustrating to deal with if you are unlucky enough to be the one getting chased: