tombot has released a two level playable demo of his DS homebrew called Steam. See the project description for the full story and instructions on how to play this game, and join the on-going discussion linked below for more information.
QUOTE(Project Description 08/26/11)
Steam is a mini-game of sorts where you (a small, unnamed robot) must match a harmony given to you by a computer. To match the harmony, you must open different valves that release notes in the form of steam. Press A to release a valve, and B to close it. When you think you matched the harmony, press A near the computer and it will attempt to match your notes with the harmony.
This is a 2 level demo, one level being easy and one being a bit more complex.
Any recommendations on the volume mix is very helpful.
No collision detection yet, but you stay within the 256x192 area so it's not such a problem.