Very good application of the Jam theme in this game. The combination of the block cooldowns, encroaching waters, and music in particular created a sense of urgency that made the simple mechanic of stacking blocks surprisingly fun. The long cooldowns meant you had to decide quickly and carefully how you use them, especially during the boss stages. Should you build vertically to avoid the rising sea level, or build horizontally to give yourself move room to avoid an incoming attack? Those moment-to-moment decisions sold the gameplay for me.
My only nitpick is that a lava bucket poured onto water actually makes stone, not obsidian 🤓