Probably been said before, but how does a traditional 2D style Oddworld spin-off game sound with a Slig as a playable character?
Just a rough idea for a possible intro,
In the events before Abe starts his run for freedom in Rupture Farms, the Glukkon's are on their usual trip to Skillya for baby Sligs, and then they are transported to a battery-hen-like truck vehicle in cages, and then loaded onto the great train to a Glukkon ran huge brainwashing factory for days of intense brainwashing strapped on conveyer belts and go through lots of interesting industrial machines, and forced to view propaganda tv's (Some don't survive) to end up becoming the drones they are known as to serve the Glukkons.
One escapes... (ermm correction)...
crawls away to it's "escape" off the processing line. This is you.
As a young Sligling, you go through the tutorial stage (Maybe as a juvenile in a Slig rebellion group, or underground survivor camp?), and once you get the hang of the ropes, and complete the tutorial, you fast forward to the time of Abe's escape. Perhaps intertwine the Slig and Abe's stories and have them cross paths at one point in time even if it's just a subtle pathcrossing?
Perhaps the character (and the content of the game) could be highly comedic (in the usual Oddworld fashion) but with a little more dark side to it's humour.... Also give the Slig the ability to pilot some pretty cool machinery in the game to take advantage of situations (
Robotic disguise Scrab made perfect for a Slig to make Mudokons flee in terror anyone?).... And have plenty of varied combat also....

Any feedback, additional ideas, anything? Feel free to post if you want to extend on this idea, or discuss about it. I'll return to more ideas later as it's 1:30AM and I need sleep.