I am also scratching my head on building a few extra environmental effects, such as moving platforms, monkey-bar style things to hang onto on the ceiling, and steam vents which will carry the player from place to place.
And for your enjoyment, here is one of the baddies you'll encounter in the first level of the game.
It's called a Dive Worm. I'm still tweaking the AI, but this creature should put up quite a frantic fight. When the player approaches its nest, the nest launches eggs in random places. The nest will continue to launch Dive Worm eggs until the player destroys the nest or 20 eggs have been launched, whichever comes first.
The eggs fly through the air and stick to whatever solid surface they hit first. After 10 seconds, if the player has not destroyed the egg, it will hatch, and a Dive Worm will come screeching out. The dive worms fly bat-like through the air. If the player comes too close, the worm will sense his presence and dive onto him. Dive Worms are not well adapted to flying for long periods of time, however, so they will often drop to the ground and pull themselves along the ground with their front legs.
In addition, this creature has a detachable bottom jaw, allowing it to double the size of its mouth when swooping down out of the sky. They are easy to kill (one hard punch should do it), but they come in packs and can cause serious damage in large groups.
I should have a working prototype of this creature into the game by the time I get my promo video up on January 9th.