The video on refrigeration should have gone over changing from a liquid to a gas more in-depth. That change uses a lot of energy. The energy needed is heat. You can design something so that a liquid turns to a gas in an enclosed area. It will get colder inside as more heat transfers to the liquid while turning to a gas. It also takes energy to turn it back into a liquid but that is done outside of the enclosure so the cycle can continue to lower the temp inside.
All stars did have the ding noise when you ran a puzzle level correctly. I needed it and save scumming to beat this. Playing this without it sound awful. IBIB!
@nodima: As someone who has not played it yet I think Jan was sufficiently vague. My big take away was that Naughty Dog will make you do something you probably won't like to progress, but I played TLOU so that isn't much of a spoiler.
GiEsE333's comments