Well, now the contest's over I can publish an expanded version of my source code with comments. Basically it was a sort-of variation of PrudentBot designed to get cooperation from So8res's stupid pseudo-mimics. The original variation had two conditions: if ((they cooperate with us if we cooperate) and (they defect against defectbot)) then cooperate; else defect. The second condition allows you to exploit stupid bots like cooperatebot, but since doing that causes all justicebots, etc etc to defect, I ended up removing that. (Though, looks like that was a bad idea in the end, since there were three cooperatebots submitted!)

Well, it's not quite a true PrudentBot since PrudentBot tries to prove unconditional cooperation, rather than cooperation-if-I-cooperate.