For September, I started a new game called The Snowball Effect. Just a simple prototype for now, but the idea is for it to be a katamari-like game where you roll down a hill, colliding into objects such as trees. The idea is to get big enough by the end of the slope so you can demolish a cabin.
A friend of mine gave me the basic idea, and I've been just expanding on it since. I have some other ideas to potentially add levels as well. This might include things like bon fires that would reduce your size, skiiers to dodge, interesting terrain maybe if I get to it. Though terrain that would be anything but flat would be rather hard with the 2d setup I currently have.
Three.js was a consideration of mine for this project, but I figured it would be too difficult to really get going in the period of a month. Presently I am more focused on developing my 2d skills, as a couple larger game ideas that I have are to be 2d as well. 3d programming is pretty fun though, as it's such a different world.