Since my brother is much into music, I somehow came up with the idea of transforming musical instruments into underseas inhabitants ... the french name "Piano à queue" for the Grand Piano may have helped ... or maybe that's just the harp-shape of hippocamps. Anyway, I've got my design and I like it.
And only when I'm done, he comes back with the office's iPad and show me the brilliant, indie-developed Squids RPG/strategy game from the Game Bakers... which happens to take place under water as well (not that surprising ;)
Although the interactions and goal is pretty simple, they managed to keep me playing until the end of the demo (that is, the point where you're prompted to purchase more characters) thanks to that lovely graphics they have. The OST is sure great as well, but it's just harder to focus on the game music with kids playing all around. At some point, I paused the game and picked my pencil to note some graphical tricks, some underwater plants I found interesting, and so on.
edit: pencils have finally discarded some sharp-harps and twisted me towards saxocamps instead. I've got other folks that look like whistling-fishes. Cymbal-manta-ray didn't make it.