Quern – Undying Thoughts is an adventure video game by Zadbox Entertainment.

The game was developed by four Hungarian graduate students, one of whom lives in the United Kingdom.

[2] The plot involves a character arriving on the mysterious island of Quern with no memory of the past, passing through a gateway which thereafter self-destructs.

There are dozens of puzzles to solve opening approximately fifty locked doors; all are needed to find a way off the island.

[4] PCWorld gave the game 4 out of 5 stars, saying it was similar to Myst of old with excellent gameplay.