If you are interested in retro game development, I highly recommend the Nintendo Game Boy or Game Boy Color as a development target. You can develop games with either Z80-ish (Sharp SM83) assembly or C. The system has most of the features of the NES, but has a ton of kinks worked… I like to think of it as a dream version of the NES.
It's really limited, though. Sometimes that is nice, but if you want a bit more of a comfortable environment, the GBA is wonderful. It's got a decently fast processor and enough RAM to not have to worry too much about it, and it's got some really interesting hardware that is easy to use but also allows lots of interesting trickery.
Oooh! I’d also love to recommend GBA homebrew development, especially if you’re a little wary of learning Assembler.
I had a fantastic time in high school, grade 11 or so (2005?) - playing with the homebrew development kit at the time…
The joy of GBA is a much broader palette - well - any colours whatsoever, if you’re just talking straight GB (no GBC) - and access to some fun hardware tricks like scaling, extra background layers; honestly - it’s like an SNES pro or something. I love it.
