To make the spiders get out of your way you have to flip the switch with the corresponding colour then run! :-)

The final level.
You need to stand in the way of the balloon to pop it.

Popping the balloon releases the bomb hanging on to it.

Now it's all about timing..

As you can see towards the end I actually messed this up and had figure out another way to do it :-)

Of course there's an end scene as well, but you're going to have to complete the game yourself to see that!