13 Thieves is a sneaky take on the sliding number puzzler, free on iOS
Threes with pirates
The goal in 13 Thieves is to reach the number 13 by combining like-number tiles together.
Instead of doubling, numbers increase by +1 each time you combine.
It's similar to Threes!, but split up into levels that you can actually pass.
Also, tiles are themed: there are pirates, burglars, and other manner of general, theft-involved criminals.
You can also do missions to receive power-ups, which previous games of its type don't have.
If it sounds like your thing, you can download 13 Thieves for free on the App Store.