Here is some code I did:
<img src="http://i50.tinypic.com/29z3i50.png" border="0" />
The code does things like checks whether it's a new level and if it is, deletes the enemies and creates new ones. The code shown isn't framerate-independent but yours will be.
I figure a metroidvania game would take me 40 hours of work. Which may take 2-4 weeks. Does that sound right for you?