It's in the bagG 10

It's in the Bag G10:
Unlock 50 Luggage of any type.

At the end of each game you get to open pieces of luggage. the more numbers you daub with the luggage icon the more you can open. you must have a key for each piece of luggage. you can earn keys by daubing numbers with key icons, or also from opening luggage. if you have more luggage to open and no more keys you can buy more with coins. after opening 50 pieces of luggage across all games this achievement will unlock.

ALSO, if you have already gotten this on the Windows 8 version, it will pop as soon as you start the Windows 8 version.

Credit goes to QuickMythril