I built these. Fathom got deep.
I make games after work with Myth Engine. Some are tiny. Some get out of hand. All of them are free in the browser.
Fathom is new. Thirty-six fathoms, a field guide, charge shots, dashes, and one very rude kraken. I started with a shooter and somehow ended up cataloging sea things. Anyway. The ocean made me do it.