Proteus (1983)

From the Kadon website:

Michael's concept was to create a meta-game that allowed for rule-changing but had a fixed slate of rules, unlike the fluid game of Nomic. The rules on 9 wood tiles determine how the players may move their pieces, trade the tiles, or even win. A rule is activated when a player's piece enters a correspondingly shaped tile, and the previously active rule is turned off. A placement phase precedes the movement stage. Experienced players can sometimes win even before movement begins. The strategy is intense because long-range moves are not calculable. For two players, Ages 12 and up.

On Omni's list of best new games, 1983.

Publisher's official page with rules