How long is Well Dweller?
The developer's estimate is roughly 10-14 hours for the main path, and completion guides put a full 100% cleanup around 15 hours. The free demo runs about an hour.
What order should I play Well Dweller regions in?
The early game is linear: Night Garden, Hunter's Cabin, The Bog, then The Drains. After that the game opens up - family rescues, Golden Feathers and movement upgrades can be worked on in parallel - until 7 Golden Feathers open Queen's Castle.
Do I need 100% completion to finish Well Dweller?
No. Trinkets, Spirits, story pages and upgrades are optional for reaching the Queen. The hard gate is 7 Golden Feathers for the castle entrance, plus 3 Elevator Parts for the Drains lift.