I would make another Abe Game. Rather than a 2D screen by screen play, it should be a 3D side scroller, with the best graphics possible with today's technology! Where Abe doesn't look like a 2D bitmap, he is instead a 3D model played from a 2D perspective...
I would then make it possible, for today's ""2D!? TEH FOOK!?" gamers to instantly, by the touch of a button, move between side scroller mode to full 3D mode like in MO and SW.
But most importantly... perhaps the most important of all... I would bring back the "Follow me" gamespeak button that were robbed of with Munch's Oddysee
What would you do? 
Also, I've become an Oddworld Discussion "O hay wt wud u do if!?" poster... Lord help me.