Worked through this quite a bit more today. I’ve now done all of the first three doors and the unlocked challenges I’ve come across so far. I’ve unlocked loads of achievements (well, only 80-ish points worth, but that’s most of the actual things to unlocks), and have rescued all of the Clydes and collected all of the Killer Kenn dolls on every level so far.
It’s a great game, but hasn’t really been much of a challenge yet.