Merge into One by Jose Varela FREE

Merge into One comes from Jose Varela. The object is to combine the elements until only 1 remains.  Look at the second image to see the rules.

This game goes pretty fast.  I think there are 40 or so levels.  I solved them all very quickly.
https://itunes.apple.com/us/app/merge-into-one/id1460578569?mt=8