yes, the whole Master System name was because it was supposed to be the “Master” System, and you could add peripherals to it. The Japanese Mark III was the Master System

They got rid of the card slot, the device was smaller, and it had an inbuilt game (Alex the Kidd in Miracle World in my case, although it seems some had Sonic instead)

There even was am even smaller version called the Master System III which I think only was released in Brazil.

The original Mark III was what would be the Master System in the west. The Mark 1 in this case was the Sega SG-1000 which had a very limited release outside of Japan (and came out the same day as the Famicom, so always had an uphill battle). The mark 2 was an iteration om that. As was the Mark 3 and the later Mega Drive actually.

Sonic 1 or 2 were fantastic and completely different from their Mega Drive/Genesis counterparts

I still go back to California Games every once in a while.

I loved Asterix, but I dont think I could stand going through that nowadays.

Golden Axe was cut down compared to the MD or the Arcade version, but still impressive for the MSII I had.

I want my wife to be able to use it without having to install anything

No shit. AFAIK Tumblr us circling the drain as it is and barely able to keep the lights on