Hmm, three way tie for fourth place.

I thought So8res was trying to set up subtle vulnerabilities for the mimicbot clique to exploit himself! My own exploit (store their size and see if it changes; if so defect, on the assumption that most who change their size will only change it once; play small-n mimicbot so you can induce cooperation on their turn and when the exploit doesn't fire at all) seems to have cut the problem a little cleaner, picking up more nonrandom DCs. I had essentially thought of this exploit in the first few days of the contest, but I had thought it would set me up for a few too many CDs (ended up getting one, but it was random) until So8res posted his tutorial, at which point it seemed like there'd be enough paranoid mimicbotters choosing a random rank on their first move (for example) and leaving the rank-choosing machinery out of their later versions for my exploit to be profitable...

...and instead my DCs were on non-quiney bots which ran simple bot tests, like the one in the contest rules' example. I did anticipate I'd pick these up, but I didn't think there'd be so many of them.

Anyway, this was good fun. Thanks for hosting, AlexMennen, and thanks for playing, everyone else.