I feel like this is a tough question to answer since being underappreciated is quite subjective. For example, I feel like Khazan is underappreciated in the sense that the game is just not as widely known as its contemporaries that shadow it (AI Limit, Lies of P etc.), so it never really had a chance to shine. It’s appropriately rated and liked by fans of the game, though.
What’s your pick?
Another Crabs Treasure probably flew under some folks’ radar for looking childish but damn that was a solid game