This was actually released in 2011/2012, but I managed to miss it at the time, and really wish I hadn't:
http://www.moddb.com/mods/quake3-hopperThese are new and improved bots that can be plugged into any other mod, including Gen Arena. Basically you get this new Q3 executable, drop it in your main Q3 folder, open it, and load anything you want from the mod menu, and it runs just like the normal exe but with better AI.
For years I've solely been playing CPMA offline because it includes improved spiterbots, and I felt the vanilla bots were just too unrealistic (zero movement and 100% aim). CPMA bots had much better movement, but some strange behavior...occasionally seeming to randomly not notice you anymore until suddenly hitting you with psychic blind direct rockets from around the corner. They felt buggy and also a big cpu hog, even in a modern rig I would get framerate drops when running them on particularly resource intensive maps.
Hopper Engine overcomes all those problems. The bots strafe-jump similarly to spiterbots, with similar item control, but with more consistent polished behavior and no cpu strain. Best of all, you can run them in Gen or any other mod you want.
Of course you can't have everything, and the downside is that they're not optimized for Gen movement. Since they were designed around Q3 movement, they play the Arena class best, and aren't quite as adept at moving with Strogg/Earth/Doom classes. Slipgate movement in particular trips them up the most, though they still do much better at it than regular Q3 bots.
Obviously nothing replaces real humans, but with the Q3 communities being as small as they are now, having better bots to mess around with really breaths new life into the game.
