OddjobAbe, welcome to the forums and stuff...
In future, please don't double post and use the Edit function, I know you're new, so I'm just telling ya!
Squeek's Oddysee and Hand of Odd were planned as 2 more quintology titles, but never made it into production.
Sligstorm was cancelled, and was originally going to be packaged with Abe's Exoddus as a bonus game.
Oddworld adventures 1 and 2 are real games, and I have the second one, the graphics are very bad, but it's a GBC game, so it can't be helped. I had a lot of fun playing it though.