Secret of the Entity

Secret of the entity is a FREE expansion, unlocking after completing the game. The DLC begins by player leaving the ship, finding captain Jetsen outside. Talking to him triggers the DLC.

The point
This free expansion adds 12 new levels. Players collect dark selfburnium in them. These levels are way harder than the story ones, Jetsen does mention that these are not too easy to get.

The twelve levels are scattered around the Entity, with 2 levels in every dimension. After every 2 levels you can enter Endera and talk with other crew members.

Every level includes 4-7 dark selfburnium. The DLC contains 66 dark selfburnium in total.

Listening to the final crew dialogue (argument about toilets) displays a white colored text on a black background thanking player for playing. If you already have all 66 dark selfburnium, the text will be different.

Activators
Levels are unlocked by searching for activators. Every activator requires some amount of dark selfburnium to be activated. The activator in crash site is free.