XMen2: Clone Wars
In my first job in the industry, I drew and animated most of the characters for X-Men 2: Clone Wars.
Working on this game taught me how to function within a team of people with very diverse skill sets, how to work independently, and how to make the most of whatever resources are available to me. Once you’ve brought the X-Men to life with 16 colors, 64 x 32 pixels, and very few animation frames, everything else is gravy. 
Here’s a video of someone playing through the one level for which I did art:
My proudest accomplishment in this game has to be Magneto’s cape in his idle sequence; flowing animated fabric in something like 8 frames!
Nightcrawler’s “bamf,” below, was relatively elaborate, but still quite efficient through compositing and reuse of elements. Notice how the smoke clouds are made up of vertical lines with gaps between them? That was a way of achieving a translucent effect in the pre-alpha-channel days. The pixels would sort of smear in the horizontal direction once displayed on a TV screen, thus blending the transparent pixels with the opaque pixels into semi-transparent color that would let some of the background show through.
Unlike Nightcrawler’s bamf, Gambit’s 3-frame idle is the picture of simplicity:
