Boxxle II came out for the Nintendo Game Boy in 1991.
It’s a straightforward continuation of the Sokoban theme, with more levels to push boxes around in.
Unlike Ms. Pac-Man and Jr. Pac-Man, Super Pac-Man was developed by Namco themselves in 1982, so could be considered the first ‘official’ sequel to Pac-Man.
The fact is: it is arguably inferior to both the aforementioned Midway Pac-Man games, which is a little embarrassing. That said: it is still a decent game in its own right; maybe not quite as ‘pure’ or ‘hardcore’ as Ms. Pac-Man and Jr. Pac-Man, but good nonetheless.
The 1982 sequel to the smash hit Pac-Man originally started out as a third party modification kit for Pac-Man machines, developed by General Computer Corporation, and called ‘Crazy Otto‘.
After legal action from Atari, GCC was forced to present Crazy Otto to Midway, the North American distributor of Pac-Man, who bought the game and developed it into Ms. Pac-Man.
Further complicating the story, apparently Midway did this without Pac-Man‘s original owner Namco‘s consent, which caused some licensing issues later. The truth is by no means clear, but in the murky world of video game licensing it is sometimes the case that people sell and exploit rights to products they have no right to.