Puzzle & Dragons is a Japanese puzzle game for Android/iOS devices. It focuses on collecting different pets (or dragons) and making them battle wild animals (or dragons) in some underground tunnels. It's like collecting Pokemon, but with a twist: you play by dragging symbols to form a 3+ connection to order that specific coloured pet to attack. So in a way, it's Pokemon with much less action and way more head-using.
Currently it's intended only for play in Japan, but the .apk file somehow found its way to the Internet. Now the game is very popular here in Hong Kong, so popular that it already spawned 2 clones/ripoffs from some Hong Kong game companies. The one downside to being able to play Puzzle & Dragons, however, is that you have to change your phone's time to Japanese time.
Why is this puzzle game so popular? I have no idea why, but EVERY TIME I play it, I get so immersed in it that I always lose track of time and constantly bump into things when I'm walking. I guess it's because it's so addicting. It makes you wanna level up, evolve and gather pets all day long. It makes you plan your moves, and make you lose track of time. Maybe...
I seriously have no clue why it's so addicting.
Just Google 'Puzzle & Dragons'.
(BTW the game is in Japanese, so you may need to search for some help on the Internet to know what to do.)