Here is the full list of all 21 The Legacy: Forgotten Gates achievements.
Completed the Clay Flasks collection.
Completed the mini-game with pyramids near the cave in under 12 moves.
Find all the morphing objects.
Completed the Decorated Skulls collection.
Completed the Deity Statuettes collection.
Completed the Pyramids collection.
Completed the Story Scrolls collection.
Completed the mini-game with blocks in front of the waterfall in under 2 minutes.
Completed an HO scene in under 2 minutes.
Complete 3 mini-games in a row without using a Skip.
Completed the mini-game with gears in the workshop.
Completed the Stone Heads collection.
Complete a mini-game in less than a minute.
Complete the main and bonus chapters without skipping any mini-games.
Completed the main and bonus chapters without using any Hints in the HO scenes.
Completed the mini-game with spikes at the pier in under 3 minutes.
Completed the main chapter on Hard difficulty.
Completed the main and bonus chapters without skipping any dialogue or videos.
Completed the main and bonus chapters without using any Hints.
Collected all additional puzzles in the Extras Menu.
Completed all mini-game levels in the Extras Menu.