Here is the full list of all 18 Mindset achievements.
Complete six packs
Complete four packs
Find two hundred hard sets
Find one hundred fifty medium sets
Complete two packs
Complete all levels
Complete fifty levels
Complete twenty-five levels
Find one hundred easy sets
Finish ten random levels
Complete a hard random level
Find a hard set
Find a hard set first on a board
Complete ten levels
Find fifty very easy sets
Use every symbol in the game at least once
Finish Training
Find any set