I know maybe snake may take too much battery, but could you make a pong game? I thin line and wireframe square ( [_] ) will only take a fraction of battery compatered to 1 refresh of the screen, so it could be implemented. I just want a fast paced arcade game on the e-ink display.
Also, I think a wireframe, 2 bit b&w version of Wolfenstein 3D would work as well with minimal battery usage (enemies are outlines, not full pictures)