Every act holds two hidden levels. They sit off the main road, nobody sends you there, and none of them is required to finish the game.
How they open
Hidden levels are opened by the relic routes in the fourth and ninth levels of each act. Which means the way to open them is to stray from the shortest path in those two levels and pick the relic up.
That chain is deliberate: the relic already pulls you off your route, and the hidden level is what that detour buys.
What they teach
Nothing. Hidden levels introduce no new rule — and that is the catalogue's discipline: a rule is only introduced in its own tutorial level, and that level sits on the main road. Teaching a new rule somewhere the player may never go would leave anyone who does not go there short.
How many
- 36 + 6levels and hidden levels
- 8rules
The second half of that number is the hidden levels — two per act. The figure is read from the catalogue, not written on this page.
If you miss one
Nothing is lost. After finishing an act you can go back, collect the relic and open the hidden level. The trail map shows which levels hold a relic and which ones you have collected, so you never have to hunt.
Hidden levels also unlock pieces of the story gallery.