My brother and I made up a version of Magic as kids where all the mana is laid out sideways in staggered rows between the players, creating a sort of hex grid landscape. You drew and played from your deck, but placed cards on the "map" created by the mana on the board, only where the adjacent mana matched their cost, and moved around attacking each other. Six adjacencies meant cards could cost up to seven and work in the format.

It was great fun, and also completely unbalanced. Once you knew your opponent's powerful card, it focused battles around the intersections where they could spawn. I've heard of other people doing similar things, but never an official format that used mana as a landscape game board.

We mostly did it that way because we didn't know the actual rules, which I recall being widely true of both Magic and Pokémon among kids who collected the cards in the 2000s.