This is a Sudden Death style micro cube.

Players grid draft 6 packs of 9 cards, build 15 card decks and play games starting at 1 life.

A player may only mulligan if they draw a hand with 1 or fewer lands, they must reveal their hand and then draw a new hand of 7. Once each player has decided to keep their hand, either player may scry N where N is the number of times their opponent mulligan'd.

The list is not perfect by any means, but it's a start and I am quite pleased with it.