Alright, I've started a new game. Or, more specifically, a new game engine. I want to perfect the engine before I start the storyline or art.

The game engine is a side-scroller (or platformer). I want some ideas from you on what I should make. The ideas can have to do with storyline or gameplay things (like power-ups), but specifically I want some ideas on what I can add to an engine. To help you understand what I want, I'll tell you what I have done on the engine.

- Barriers: walls, ground, platforms that you can jump up on from below, and platforms you can't jump up on from below.
- Movement left and right, "camara" following
- Jumping
- Enemies: enemies that move left and right that only change direction when they hit a wall, and enemies that do the exact same thing except they also jump constantly.

So, along those lines, do you have any good ideas for my engine?