One of the best maze generators I've ever seen was in the ZX Spectrum (Timex in the US) game of Steve Jackson's Warlock of Firetop Mountain[1]. It's brilliant, coming up with a maze full of rooms and doors, with no islands, and relatively well placed monsters and items. And all in 48K of ram. Despite browsing the source code a couple of times I've never figured out how it actually worked.

[1] https://en.wikipedia.org/wiki/The_Warlock_of_Firetop_Mountai...