This was going to be my CC12 entry (I'm REALLY SLOW at making levels, to those of you who don't know), but when I went to test the gimmick, I realized it was too buggy to be reliable, meaning the half-baked idea I had for a neat level is now relegated to gather dust under Casual Levels. I'm still releasing it since there might be someone who can figure out how to get this to work (but be warned; I tried various NPCs, and each time,
something went wrong).
That door is the gimmick. The reason I didn't make the mushroom block invisible is so the player can witness my gimmick fall apart before his/her very eyes.

--EDIT--
Wow, I just figured out what I was doing wrong. I feel so stupid. Well, it's too late for this to be a CC entry now that I released it. Aaargh....
http://www.mediafire.com/download/bh66g ... tition.zip