All-purpose controllers are cool for emulation as you only need one for multiple systems and it should just work. But with things like FPGA, there’s a strong case for having dedicated controllers for their respective systems and they’re not always easy to come by.
That’s what makes Retrostalgia’s USB-C Master System controller mod so cool. In the video, we see how they cleaned up an original SMS controller and put in the necessary component (namely a RP2040 Zero board).
Now you can emulate Alex the Kidd and Phantasy Star with some of the original hardware.