I sketched an entry for the original contest while on vacation, but by the time I went to write it up (before Sept. 1!) submissions were closed. My sketch looks very similar to 18-87/TFT-2D, and (as I recall) the relevant parts of the reasoning that led me to it were:

• a TFT variant will win, so I'll write a TFT variant
• clearly the winner needs to beat TFT so I'll defect on the last turn
• most people will defect on the last turn so maybe I'll defect on the last two turns
• (I don't care about the elimination thing, only the evolutionary tournament)
• given that I'm around in the last few generations, I will compete against me, so I'd like to not defect against myself in the last two turns
• I'll pick some arbitrary turn to defect on like 56, and if I see that we both defected on 56 then I'll cooperate for the last two turns
• ...but 1/1,4/4 is fewer points than 0/7,7/0 so it'd be better if I could defect on different turns against myself
• fine, randomly between 50-80, and on turns 99-100 if my opponent acted like TFT except for a single defection, then I'll cooperate. Or okay, why not 1-95. No, people will probably do silly thing in the first few turns. And last few. 18-87 or something.

I'd like to see competitors' reasoning for their submissions.