See first video and world 4 part 1 for all details.
0:03 Toxic Fortress: Here's the sister level to Sulfur Laboratory, and it plays out slightly differently once you get to the second half. The second half features a bunch of moving layer 2 water tides / moving ground.
5:44 Dontspin Fortress: Originally named Twister Fortress and based on spin jumping, this level is based off of NOT spin jumping. If you spin jump in some places, you'll break the turn blocks and fall to your death. In the second half, it adds layer 2 and ON/OFF controlled light switches, and finally, another Big Boo boss with layer 2. Wow!
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