Apparantly I missed one possible option, so I'm just pointing that out here. There is a "trick" with Blinking that allows you to do some funky stuff - including pass the green gate in the sewers without the green key. The problem is that there is no "blink" on the other side, meaning you will get stuck with no way of getting back, and you will need to revert to an earlier savespot.
So - don't pass the green gate in the sewer unless you open it with the green key, as intended!
BTW, no level requires the "blink trick". It allows for some interesting adventure solutions, but every single adventure can be solved with just regular blinking.
(in fact, I think I will remove the "blink trick" in a future update, since it does open up too many possible trouble spots. So try not to use it, kids!
)
