That sounds like a great idear...
But do you think that the master planet would be like the sun in that it would be the prim energy sorce to Oddworld. Or do you think that the sun is the sun and thats all their is about it?
Maybe if the sun is the energy sorce of Oddworld and Oddworld rotates at the same speed as its orbit (like our moon- but moons do rotate differently aswell) its loonner months would be its days... And if Mudos was on the side facing away from the main planet then thats why we havent seen it yet also...?
It could also be that oddworld is in a sister planet sistem where it orbits around a planet of a simular size as its self?