Really cool idea! It reminds me of the goo in Portal 2. I love the mechanic, but I do agree with some other commenters that saying "Jump!" on the hill is super misleading. The only reason I got past that section was because I somehow accidentally double-jumped... Lastly, the "???" idea for the green goo seemed cool, but I got stuck on the huge wall and I didn't see any effect from the green goo. So it could be a good idea to explain what the goo does at some point.