Not entirely software, but the MiSTer FPGA project. Having accurate zero-lag hardware accurate versions of almost every console, many arcade games, PCs (Amiga, Commodore etc), and handheld up to and including the PlayStation in a box the size of a game boy is unreal.
Majority of the project is open source, and has been used for ports to the analogue pocket handheld, which I also have and use often
Not entirely software, but the MiSTer FPGA project. Having accurate zero-lag hardware accurate versions of almost every console, many arcade games, PCs (Amiga, Commodore etc), and handheld up to and including the PlayStation in a box the size of a game boy is unreal.
Majority of the project is open source, and has been used for ports to the analogue pocket handheld, which I also have and use often