Tetragon Achievements Here is the full list of all 12 Tetragon achievements.Filter Achievement View View Image viewList view Sort by TrueSteamAchievement desc TrueSteamAchievement asc Achievement name desc Achievement name asc TSA Ratio desc TSA Ratio asc Gamers desc Gamers asc Steam order Date won desc Date won asc Flag Filter All None 12 Offline Mode 12 Single Player 5 Main Storyline 2 Collectable 4 Missable Link flagsOR joinAND join Achievements without these flags What are achievement flags? Click to find outApply Searching for ghostsFind and interact with all ghosts of your son The Tetragen's rebornFind and collect all the fragments of the Tetragen Fruitful ForestComplete all levels of Fruitful Forest The Witch's HouseFind the secret level of Fruitful Forest Gnik CastleComplete all levels of Gnik Castle Giving UpEntry on the portal on the Dungeon Level Release the prisonerRelease the creature on the last level of Gnik Castle Deep WoodsComplete all levels of Deep Woods The Secret CaveFind the secret level of Deep Woods Ancient StonesComplete all levels of Ancient Stones The End of TetragеnFinish game without all the fragment of Tetragen The Return of the JewellFinish game with all the fragment of Tetragen