Game is completely completed
All levels are available for replay
All eggs are found
Secret level is unlocked

Path:

Root of the installed game/Steam/MEX/

Access to the secret level:

Load episode 26 (picture with a flying insect)
Go left and go down the stairs
Run right into the darkness, along the way we climb onto the ledge and go through the open gate

Author: SuN1Sh1nE