[drakan90]

Yeah, we know.

"A sad ending is dissapointment, it means the Quinteros haven't done something right or good for oddworld. If they have, then we would be happy and thus making it a happy ending. That's what I'm hoping"

Not necesarrily.
It depends how you look at it.
If you think the characters making a difference, and everyone going hooray peace on oddworld! Love and...other such shit! would the the 'optimal' kind of happy ending.
BUT, seeing as they're trying to save Oddworld, it could end up with all the characters being massacred/giving their lives, but the planet becoming balanced and natural again, thus could be considered a good ending. (That examples a bit extreme, but do you understand what I mean?)