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