Adaptive tile refresh(link), this is nice rendering technology, i hope away3d 4.x can implement such rendering technology

If you’re re-making Commander Keen you might want to start with a 2D molehill engine. I know there’s a few under development.
http://www.nulldesign.de/2011/03/10/nd2d-molehill-2d-engine/

Adaptive tile doesn’t really apply to 3D, as generally the entire screen needs updating all the time.

Good Luck!

Thinking about it, this is already implemented in Flash 2D.
If you have the debug player and right-click and select Show Redraw Regions
you will see it in action. Here’s yet another 2D framework…
http://starling-framework.org/

Away3D 3.x uses this. If the look of an object (from the camera’s perspective) hasn’t changed, it is not redrawn unless you do a force update. It was implemented by Rob Bateman.

I’m not sure how much sense it would make in a GPU graphics pipeline, but its sure worth a thought.