Sorry if this is a stupid question ... but I can't remember if this feature made it on the list or if this is something that only MIGHT come in at a later stage:
Level jumping system that retains the levels last state
With this simple but effective feature, you can create non-linear story-lines and expansive worlds to explore. All game states are preserved between level hops, meaning the pile of bodies you left lying around will still be there when you get back from your hop to Mars.
It's something that would be quite important for the kind of games I have in mind creating.
Thanks for any hint or info anyone can provide on this matter.