Hmmm... your description rang a bell but I haven't found it (yet) - sorry
I've zoned something
technically (not artistically) similar-ish. If it's Calvin you seek you'll be disappointed. If your focus is more
barebones-fullscreen-copper-chunky-rotozoomer-ocs-in-a-frame then it may temporarily scratch an itch.
From memory: 352x284 overscan 8x4 rotozoom + hires (ocs) in a frame. No sprite masks, no blitter, no audio, 100% vanilla cpu/copper. Not particularly optimized as it already fit with room to spare (add.w/move.w per texel (4096 col)). No artistic merit at all. 'Pang Bubbles' != 'Calvin & Hobbes' unless you really squint hard.
I'll keep looking...