Another game idea (that would be quite easy to program):
First, you launch the game, and the game records the time you launched it and then exits.
Then, you launch the game again, and you get a score based on how long passed since your first launch of the game. The longer the time interval, the higher your score.
*But*, there is a catch; if you took more than 20 minutes between your two launches of the game, you fail and get a score of 0.
So, in other words, you need to run the game, then run it again as close to 20 minutes from then, but not go over.
How does this game sound?
(If you have some programming knowledge, this game should be easy to write.)