One of the most interesting features to add in a platform game is the double jump.
This means the player can jump, and while in the air, can jump once more to get higher platforms.
Something like this demo made with StencylWorks, taken from my upcoming game Kira the Witch:
Move with LEFT and RIGHT arrow keys, jump and double jump with UP arrow key.
I already showed you how to make an actor jump in the post Create awesome Flash games in no time with StencylWorks – adding intro, jumping and more, but when we want a double jump, we need two more attributes: one to see if we are jumping, that is if we are in the air because we made a jump (and not because we are falling down a platform) and one to determine if we can perform a double jump.
In the end, the double jump can be made only when you jump, and before you touch the ground you release the jump key and then press it again.
That is, the behavior you can see here:
Useless to say, really easy, like all StencylWorks features.