I did a little actual thesis revision today, and quickly slacked off by rewarded myself for my Hard and Virtuous Labor by playing with approximating cubic splines in Flash. Flash, as you may or may not know, is a cheap bastard, and only gives you quadratic splines. Truetype is also shitty this way, but I've always relied on fontforge to do that dirty work of conversion. I was kind of curious how you'd go about doing it, and I enjoyed doing the puzzle from scratch of how you subdivide one cubic spline into two cubics, and how to decently approximate a cubic with two quadratics so that everything is at least C1 continuous.
It's not an exciting game or anything, but here it is. You can move the control points around, and change the "method" (i.e. what it does at the base case of recursive subdivision) and how many levels of subdivision it does.
Now if someone wanted to take Line Rider and make "Spline Rider", that would be kind of cool. With like elasticky stretching splines or something.