Loved it, specially the name.
It goes from "I don't understand how it works" to "ooooh" as soon as you understand the implications of "Whoever locks the last board looses the game".
I read on the devlong about how this is your first jam and an advice/feedback I would give is about the game's controls and rules: There's a decent chance a player won't read the game's page on how to play and even if they do, there's still a decent chance it just didn't stick on their minds.
I think even a single right sentence like "Don't be the last to place a piece" or "Try to lose" would be enough to make players understand once they have the context during the game, but not by reading it before.