Good concept game. The devil is in the detail. Too bad Retrochess, with each move a retraction by definition, has a lot of problems going from century-old Problem Theme to any playable CV. Not only retraction, each move by worthy rules has to be an Un-take up to a point actually, or else games go on forever. See comments in the article as well as these same ''all comments.'' Nothing would be seeming to work right all the way down the line. The best solution, not yet mentioned, is to give up on 8x8 and play them standard Los Alamos 6x6. Or at very most some deviant Congo 7x7. All dealing with is another of several hundred available Mutators, applicable to all the 4000-6000 cvs around. Still, it is good to try for 64-square embodiment, just don't publish til getting it right. After all, what involves any annotation, say hypothetical Kasparov of some hypothetical Anand-Carlsen, but ''retro-analytic,'' computer-driven post mortem, rather kin to this same thing of Betza/Neto, made into the site-compulsory cv game? The technical chess term instead refers to the constructions linked at two outside in CVPage article ''Retrograde Analysis Corner,'' not regular annotation in f.i.d.e. of course. In Betza/Neto here, how long to reach ''no legal retraction'' and the flurry of problems addressed should be soluble at once on 1950s Los Alamos; and the reverse-play of that one may even become non-trivial. Unfortunately it is dangerous rashly to get more specific generalizing the ''Retro'' class -- required Un-takes only every second or third move and all that -- to alternative cvs. The category was just fine as a problem theme all the 20th century until Betza gummed it up.