Here is the full list of all 12 Marble Mountain achievements.
Fall at least 10 kilometres over any number of playthroughs
Launch from the treetop
Finished all Levels with Gold Banner
Cause 50 evil skulls to fall to their death
Finish the game
Find the resting place of Mr Jones
Make it across the Trap Door Puzzle in under 7 seconds in 'It Burns'
Achieve Max Speed
Completed 'Graveyard Depths' without slowing down the blades
Finish 'Loot the Temple' the quick way.
Complete all levels in under 80 minutes
Finish all Levels without dying