I've gotten fully stuck on Chapter 2 of the Ice Caves, at the puzzle depicted here: https://ibb.co/wsdT79s I can turn everyone blue, but then I can only get either myself or the snow crab into the bottom blue elevator, but not both. Any way someone could take pity and give me a hint?...

What's the exact triggering condition for this achievement? I went into several positions that technically fits the description, but not luck for the achievement.

I just completed the more complicated solution where you walk through the yellow door at the top of the level instead of the green door. The solution was much more complicated but felt intentional the whole way through. However, nothing happened as a result. I just finished the level like I did with the easier solution. Is this intended? Even an achievement would've been better than nothing....

went to check ---- just says "purchase"

Am I supposed to open the green door with that round thingy I can pick up? If so, how? If not, what else is there to do? Is this as far as I'm getting on Linux (using a custom fork as Steam's Proton versions didn't get the game started)?