If you really want to get esoteric and hackish, the Cinematronics vector games of the era had NO microprocessors in them at all. It's all bit-sliced TTL gates and EPROMs to hold the object code. Wrap your noggin around that one.
About the same time I was playing too much Atari Star Wars I was also using HLH Orions on my CS course - the early models had bitslice based CPUs and had user programmable microcode:
