Here’s a project I made back in 2006: a portable Intellivision. I took a cheapo LCD TV and combined it with a 25-in-1 Intellivision game toy, and managed to cram the whole thing into the shell of a broken gameboy. The whole thing worked out pretty well, except for the portability part. There wasn’t room in the case for a battery pack, so it had to be plugged in to work.
It ended up as a present for my friend Kevin, in remembrance of some fun we had in college when we wrote Fish Fish, a clone of the Intellivision game Shark! Shark!