I was interested in attempting to categorize how the games this round related to the theme.

You can take a look at my work in progress here: https://github.com/evilseanbot/ld29cat. If people want to suggest additions submitting a pull request would be the easiest way.

Some rough statistics about the games I played:

• 22% are set underneath the water or have an important element underneath the water.
• 49% are set underneath the ground or have an important element underneath the ground.
• 10% involve removal of dirt tiles via digging, explosions, lasers, etc.
• 5.3% involve being “Underneath skin” (Including my submission)
• 5.3% are platformers where there are characters on two sides of a mirrored surface that are controlled simultaneously.
• 4% you control submarines.
• 1.3% you control a scuba diving bear.