Marketplace is the tenth and final main level of Doorhaven. It tests the player with a large amount of Bulk Keys and Bulk Doors in various colors, challenging the player to open the correct doors and collect the 6 required white keys to win.
Description
Here's a good puzzle to send you off after your stay in Doorhaven! The goal is simple: Bring 6 White Keys to the door! How you manage to do that is for you to figure out. Good luck!
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Puzzle Logic
There are not enough keys to open everything, so some doors must be left behind. The "count the locks" skill used in the previous level can help to determine which doors to ignore.
Purple: There are 16 purple keys and 20 purple locks. 4 purple locks are not used.
The 4 unused locks are behind the white door. Opening that white door would defeat the purpose of going after the white key in the first place. All other purple doors can be opened freely.
Orange: There are 8 orange keys and 10 orange locks. 2 are not used.
Because purple can be opened freely, there is no reason to use the orange 2-door to get the center key instead of the purple 2-door on the left. The orange 2-door near the center is the unused one.
Green: There are 4 green keys and 8 green locks. 4 are not used.
Because the center orange 2-door is ignored, so is the single green door there.
The passages with green 2-doors are strictly worse than the double cyan passage at the bottom right. One green 2-door will go unused.
This leaves 1 unused green lock to account for.
Cyan: There are 4 cyan keys (2 of which are at the bottom) and 9 cyan locks. 5 are not used.
Opening the cyan 3-door prevents spending any more cyan keys. This is strictly worse than opening the double cyan passage. The 3-cyan and single green door will be ignored. This accounts for the 1 missing green lock.
Considering the number of steps needed to solve the level deductively, many players may find it easier to solve this level through trial and error. However, examining the logic of the puzzle can sometimes give useful insights into the design process the developer may have used to create the level.
Solution
Collect all keys, head to the bottom-right, and open the 2 cyan doors to get a white key.
Open the bottom 6-purple and 2-orange doors and pick up the 2 cyan keys.
Open the purple 6-door on the right and pick up a white key.
Open the top 2-orange, 2-purple, and 1-green doors and pick up a white key.
Go to the left, open the 2-green and 2-cyan doors, and pick up a white key.
Open the top-left 4-orange door and pick up a white key.
Open the middle green door and purple 2-door and pick up a white key.
Take the 6 white keys and open the 6-white door to get to the goal.