Here is the full list of all 10 Spoiler Alert achievements. It takes around 1-2 hours to unlock all of the achievements on Windows.
Get gold star score in all 10 levels in the Mariachi World.
Get gold star score in all 90 main levels.
Uncomplete the main game.
Find all 3 hidden main treasures.
Unlock all 3 main worlds.
Do the leap of faith in World 3, level 12 - without middle landing on the support block.
Jump more than 150 times.
Get squished flat as a tortilla.
Cause more than 10 time paradoxes.
Watch the credits from finish to start.