Swap and match happy pets to form chains of 3 or more of the same color. You will be rewarded with explosive power-ups if you match 4 or more.
Tap on the happy pet and swipe towards the one you want to swap it with, You will need to have 3 or more identical pets lined up with each other to remove the chain. Use power-ups by tapping on them on the top of the screen. You get a power-up for each level you successfully complete.