It's a nice level you got there, and I can see how this got 14th place (good job with that).
There are however some small things I want to point out (I tend to be nitpicky about some things):
- The message box in the beginning swamps you with information. You can leave out the text about the red coin p-switch, or move it to before the actual p-switch. The crystal mushroom doesn't really need the explanation, because of the text when you grab the crystal mushroom itself. But you could also use a switch for this part and delete the crystal mushroom altogheter (unless they are all used in the second part).
- I've never encountered a mystery warp box before, and although it is explained in the level, I still wonder why you didn't use a normal warp pipe?
- It would be nice if you got a little bit more time to get all the red coins.
- I like that you get two yoshi's out of each block, in case you are with two players.
- The mushrooms keep coming out of the mushroom block here:
- There was a sign in the second half making a joke about another community. Such a reference doesn't make sense in SMWCX (especcially because it's saying "this community", but it's not refering to SMWC).
- It would be nice if you put down arrows above this hole:
The first time around I thought it was a dead end and went back :/
These are all just minor complaints, and overall it was a fun level. Keep up the good work.