Is there anything wrong with the top bots being single gene?
Only that they are much harder to write than the normal bots. The leagues were never intended to be a showcase of just the best writers, they were also meant to provide an obtainable target for new players. If it were otherwise then, right back when I first started competing against PY, the league would just have been a long list of bots by me and him! (Not saying we are the best bot writers just that we were, literally, the only two competitive bot writers at that time and we made a decision not to do that.)
I agree with Henk, a seperate MB league (the acme of bot design), and archiving both sound great ideas. I am waiting for Eric to sort a version out with working leagues before all this happens as well, it's just a bit of discussion first.
PY, has, in the past, put an awful lot of work into keeping the old bots up to date with newer versions of DB. Many of the old bots simply wouldn't work still otherwise. It's not something I have the patience to do, I'd just scrap 'em and write a new one and PY doesn't have the time to do this any longer. Not something I'd expect volunteers to be crawling out the woodwork to do either. I would suggest we stop worrying about backwards compatibility as much as we have been. (Remember the dinosaurs?)
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Paradigm (seeing as that is a popular word atm) for new leagues! (Using DB version that Eric recommends)
MB league - Old rules apply - Any of the old MB's (without redesign) that still work will be entered to create starting league
Free for all league - As it sez on the tin! - Any of the old bots (without redesign) that still work will be entered to create starting league
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I won't put a max length on the FFA league until it starts to take to long to run, (anybody should be able to beat the bots at the bottom of the league without real problems). The only rule I might consider is a 'sploiting rule. It makes it a bit easy to get to the top (from experience ) but does highlight problems with DB. If one type of bot turns out to dominate then either a new league will be created or pressure will be put on you all to figure a way to even out the playing field.
I think I still have a file somewhere with most of the bots that had been written up to a certain date but I'm not sure how you'd suggest archiving stuff.