'Robot Destruction' the way you describe it rather looks like something that could be AngelScripted, instead of being hardcoded into Plus.

Of course I'm no scripter, but I'd imagine making a few custom robot enemies and defining rules on how and when they spawn are a proper base for such gamemodes.

Actually, I thought about some JJ2 'horde' mode a while ago. As in making waves of enemies spawn in Battle maps, which become harder and in greater numbers after each cleared wave, with a chance to resupply ammo/health inbetween them. Then there could be a boss wave once every 10 waves or so. Man, I should learn to use AngelScript sometime..