Not counting breaks (eating, sleeping, etc.) I spent around 24 hours on this, give or take a few hours.
I did bring in some pre-existing code such as fixed point math, but I actually ended up not using it at all so that was deleted.
I started writing it in Java, but I threw all of that code away and decided to switch to C. This was going to be a first person shooter at first (like Wolfenstein 3D), but my brain was getting a bit fried and time was short so I decided to make a platformer instead.
The sprites (all 8 of them along with 10 digits) I drew with my tablet rather quickly.
I explained a bunch of the gameplay away as story since I ran out of time to properly fix some things and implement them.