Someone (you?) linked this here and I ended up buying Q3A and running it through ioquake. Quite a blast, even with just bots.

Not nostalgia for me, I play Quake 3 about 15 times a week with a group of people, it's still awesome fun. We're all so good at it, it's genuinely a difficult competition every time. After 15 years we still get in ridiculous/interesting situations in the same maps all the time.