Last weekend I made spent 48 hours making a game from scratch for the Ludum dare game jam. You can see the various videos I took during its development below (in reverse order of course :p).
Binary available here: https://github.com/8BitPimp/ldjam/raw/release/ld36/surge.zip
It was an absolute blast to make and I learned so much during the 48 hours of its development.
Some key learning points were Finite state machines for enemy sequences. Lissajou curves and hermite splines were used for some of the enemy and boss movement patterns. I also had my first experience of using SDL_Mixer as an alternative to my usual choice of bass audio.
In the preceeding week, I had ducktaped together some of my previous small projects, so I was able to leverage a nice spatial hash implementation I wrote to handle all the collisions. I also made use of a reference counted object library I made with an object factory and very simple RTTI. These elements all worked as well as I could have hoped, requiring just a few tweaks during the compo.
I also think the vector version of the game looks pretty neat and could be and aesthetic worth exploring in the future.