Recs.
Updated
Badland is a side scrolling action/endless runner game that is free to play and includes in app purchases that range from $1.99 - $5.99 per item. The highest priced in app purchase being one that unlocks the full content of the game at a singular price.
SpecsUpdate
Pros
Pro Trial and error gameplay
It is only through trial and error that a player will figure out what is dangerous in a level and what all of the different powerups do. By forcing the player to try things over and over until success the game exponentially elongates the amount of time spent playing as well as makes for an interesting way to learn the full mechanics.
Pro Excellent variety in power-ups and puzzles
Power-ups that make the fuzzballs grow larger or smaller, clone themselves, get bouncy or sticky among others have to be used to get through a selection of great, creative puzzles. It keeps the gameplay fresh and varied throughout the experience.
Pro 40 free levels and 80 in the full unlocked version
For players that do not purchase the in app purchase to unlock the full title there are 40 free levels, of which after the first 10 there will be in game advertisements. For those that do pay for the full game unlock there are 80 levels to play through, ad free.