Trolls vs Vikings might be another clone of Plants vs Zombies but it still is one good game in its own right. This strategy defense game is developed by Megapop and currently has about 100k to 500k in downloads in the play store. That many people gave it a shot mainly because it is worth it.
Anyway, I downloaded and played this game myself and found it quite entertaining and addicting almost like the PvZ game. The mechanics, the neat graphics and animations are really its core and probably the reason why its easily a likeable app.
If you want to see it in action, here is Trolls vs Vikings android walkthrough I made which shows gameplay throughout the first levels.
Download this game
here.