4. Plants vs. Zombies 2
Google Play Rating: 4.4
iTunes Rating: 4.5
The first Plants vs. Zombies game was a real refreshment to the tower defense genre and gained a critical acclaim due to its addictive nature and variety of content. The sequel brought more of the same, and the best thing is that you can play it on both Android and iOS devices offline. The game is free to play, but certain in-game purchases can help you beat the game faster.