the game boy is the perfect game platform imo. there are >100 million hardware units in existence (probably one in your junk drawer); the hardware is low-power, portable, well-documented and user-serviceable; free, near-perfect emulators run on basically any platform. there are several foss dev toolchains, and the limited capabilities of the machine means naturally lower dev costs. and it's not online so it's basically impossible to make exploitative free-to-play shovelware