Ashley , some of the things mentioned here and on other posts are not cookie-cutter engine features. To name a few:
1) A basic platform path finding,
2) A more accurate path finding that can be used in a grid basis,
3) A proper lighting system that is integrated with the ability to have normal maps on the same spites,
4) A masking system that allow any sprite and/or layer to act as a mask upon any other sprite/layer,
5) A text object that supports basic formatting options (bold, italic, underline, color change, size, font, alignment) to be changed within the same text, as well as some scrolling-typewriting functionality,
6) An animation timeline to create key-framed animations that can be triggered with actions!!!
7) Support for curves and curved path movement
8) A way to have any 3rd party plugins auto-update
9) To have behaviors intertwined in a manner that they can coexist and be self aware at the same time (have physics, platform/solids and sine based movements interact for example)
These are of the top of my head and I don't believe they are either niche features nor too genre specific...