PAC-MAN MUSEUM+

When in your arcade, press then select 'Customize' then select a square. Use / to select the 'Decoration' tab to choose some balloons (the 'Balloon gates' do not count). You'll need to place all 4 different sets of balloons in to your arcade at the same time and exit the menus back to your arcade to get the achievement to pop (there is a slight delay before it does).

Here are the 4 sets of balloons, the game they're awarded from and how to get them: -

Cute Balloons - Pac & Pal - Clear 5 rounds (doesn't have to be in 1 game)

Chic Balloons - Pac-Man Championship Edition - Get a score of 1000,000 in Extra Mode 1

Cool Balloons - Pac-Man 256 - Get a power up's level to 8 - (You get side missions to complete each time you play, which carry across to your next game, until you complete them. This will vary from 'Eat 5 Cherries' to 'Kill 20 ghosts with the Laser' etc. You'll get a notification during your game that you have completed one and, when it's game over, you can collect your prize, which will be a box with a random amount of coins in it (I think the minimum is 64 and max is 512). You'll need to collect 4092 to get a power up to level 8. There are also coins in the maze to collect, +4 for yellow and +10 for red.)

Colorful Balloons - Given to you at the start of the game and will already be in your arcade unless you removed them.