You ain't done nothing till you coded a 3d engine on a HP48 GX: 131x64 pixels and a 4-bit Saturn CPU. The timing tricks to extort four shades of gray from the monochrome screen were awesome.
This reminds me of this game for HP48. It had some pretty graphics for the time, using 4-grey colors with LCD timing tricks.
Unfortunately, it also meant the game was heavy (40KB!). And even more unfortunately, some HP48 emulators (most importantly the Android ones) do not support 4-grey graphics, making the game unusable... :(
