Chessers with Nightmare Chess cards. Some interpretation was necessary for some cards, but games have been played to completion (mostly involving SteveHaas
as participating players). Time limits were mostly stricken, and the game was played as turn-based. (Or rather, the one time we tried to play on a timer, it was horribly horribly broken).
There was a movement at one point to make Chessers specific cards, but i don't think this ever got very far.
Another 'favorite' with Nightmare Chess cards was NightmareOverlay?, or even better, NightmareAliceOverlay?. See OverLay for a description.