Total Recall/WMG

What the sequel would have been about...
Everything that happened was real. Quiad and Melina are living happily on Mars. However, Quiad has been having nightmares, and they're about Hauser. He wants his body back and tries to by controlling Quaid's "body". Almost like a Jekyll-and-Hyde scenario. Richter is probably still alive, and wears robotic arms. He becomes the new Big Bad.

Recall is an early implementation of Dollhouse technology
Before it causes all the trouble on Earth. Maybe it was Quaid's failure to go back to his original personality that made them create the call-and-response feature that keeps dolls in line.

It really happened

 * If it weren't why would Quaid, a mere construction worker, be have the physique of Arnold Schwarzenegger?