I’ve been charmed by physics puzzler Vessel ever since I first saw its liquids in action, sloshing, spilling and trickling around as gravity intends. I wanted to be set loose in its steampunk world, to jump in puddles and catch raindrops in a bucket. Vessel had different ideas. It would let me play, but it also wanted me to think and it wanted me to think hard. Here’s wot I think about that.