In each episode (quest area), there is a hidden slot. This hidden slot is typically located just before the portal to the next episode.
To unlock the hidden slot, you must complete the episode’s quest by collecting all of the required collectibles.
Each episode has a unique set of collectibles that can be acquired by spinning on the slot machines in those specific episodes.
For example, in Episode One, we need to collect all of the hermit’s birds in order to unlock the slot machine Dragons of Nanjing.
You can collect items by simply spinning! Please note, however, that you can only collect one type of collectible per slot machine. Make sure to play every slot machine in each episode to gather all of the collectibles!
To track your collectible progress, look for the collectible tracker in the upper left of the episode’s slot machines.
When you have collected all of the necessary items, the hidden slot machine will unlock for you to enjoy! You will also receive free bonus coins for completing all of the collectible gathering in an episode.