Thanks for the feedback guys!
More on the machines: they're more or less "simple machines" that can manipulate platforms in various ways. eg. a wheel can move platforms around in a circle, and a lift can, well, lift platforms. Also, overlapping machines can be chained.
and yeah Impact/HTML5 is great! It's super easy to work with and even easier to distribute
Alright, I've basically got the mechanisms down. I have two simple enemies as well as the wheel and lift I just mentioned. I'll have at least one more of each & a boss, but before that I'm going to design the first level to make sure it actually works.