A new open-source mod aims to transform Sega Genesis / Mega Drive consoles in one fell swoop.
Called "Open Heart", Dustin Odell's mod uses a Raspberry Pi Pico or compatible board to add TMSS bypass, a dual-frequency oscillator (for switching between NTSC and PAL), in-game reset and an overclock.
This mod effectively gives you a region-free console as well as a system which can deliver a processing boost to improve certain games—although it should be noted that overclocking, which is not enabled by default, can cause some titles to crash.
"Overclocking sets the CPU to the master clock/5 (stock is MCLK/7)," says the project's GitHub page. "This is about 10.74MHz on NTSC. Most games work well with this with a few exceptions of mild graphical glitching, but since this is out of spec for an 8MHz rated 68000, your results can, of course, vary."
To trigger the in-game reset, you have to hold down A+B+C+Start for a second. The overclock can be enabled by holding A+Start for a second. To switch region, the console's Reset button has to be held down for three seconds. The region is retained when the console is switched off.
If you fancy giving this a go, then head over here.