I made a mistake with Terraforming Mars and learned the hard way
Spirit Island is the cooperative game I return to more than any other. The asymmetry is real — not different starting positions, but fundamentally different playstyles. Playing Vital Strength of the Earth feels nothing like playing Lightning's Swift Strike. The different powers, different board positioning, different invader targeting priorities all mean that every combination of spirits genuinely creates a new strategic challenge.
The adversaries are where the game becomes endlessly replayable. England increases settlement speed in ways that punish defensive strategies. Brandenburg-Prussia makes Ravaging more explosive. Each adversary at each difficulty level changes which spirits become stronger and which become less effective. A spirit that feels overpowered against a basic setup might be genuinely hard against a high-level adversary.
Jagged Earth adds eight more spirits and the Jagged Earth island board, which changes geography in ways that force different positioning strategies. Horizons of Spirit Island is an excellent low-price entry point if you want to try the game before committing. The complexity is high but the payoff at higher player counts is unlike anything else in the cooperative space.