Well, with only one day to go, it seems like I might be able to just about make it, if I work hard tomorrow.  I wasn't sure at first whether I'd be able to turn the vague concept I had at the start into something that plays like a game, but it is starting to feel like one.  The goal of the game is to supply cities with power by building an energy grid, but the lines can overheat and break down if the current through them is too great.  As the cities are powered, they also grow in their energy demands, so it gets quite hectic trying to keep the grid functioning.  The game actually properly simulates an electric circuit using Nodal Analysis, so you could even consider it a bit of an edutainment game showing how resistors work.

Right now, the cities grow at a very rapid pace, which I need to reduce if the gameplay is going to last longer than a minute.  I will also need to add some periodic upgrades in order not to make the game impossible after a while.

Tomorrow, I need to work on the progression, and add some sort of scoring system and a currency for upgrades.  The trick will be balancing everything to keep the challenge level just right over a longer play session.  I probably won't have the time to do all the playtesting that will be required for that.