Here's an idea i had for a game that would be implemented in Macromedia Flash (so it could be played online).
each level has one or more fixed SOURCES, and one or more fixed SINKS.
from the sources emerge particles, which are attracted to ATTRACTORS and repelled from REPELLORS.
some of the ATTRACTORS and REPELLORS are movable.
object on each level is to move the attractors and repellors in order to get the particles to the sinks.
Attractors should be like the bug zappers so that particles get incinerated when they come in contact with them.
Maybe user can adjust strength of attractors, and maybe some other parameters (function parameters determining strength as a function of distance?)
Not sure how to score it - maybe like lemmings, each level has 1000 particles, which start emerging slowly and speed up over time to some final time. Each level has a certain # of particles you have to get saved in order to pass the level. Score based on number of particles saved, plus a bonus for speed.
(user can speed up or slow down the rate of particle emergence, though there will still be a threshold timelimit).
If anyone codes this I'd love to host it on DonationCoder.com and offer a prize. It's not quite a coding snack - i think it would take more than a day to write.
Bad illustration of concept: