Two 9s - merge numbers puzzle is an addicting puzzle game available on iPhone. The game challenges players to tap number chains in order to merge numbers and increase their value. For example, tapping a chain of 1s will create a 2, while tapping a chain of 2s will create a 3, and so on. However, merging a chain of zeros will result in a single zero.

The ultimate goal of the game is to merge at least two nines together. Along the way, players can utilize two power-ups: Swap and Hammer. The Swap power-up allows players to switch the positions of two tiles, excluding the nines. The Hammer power-up allows players to smash a tile.

While the gameplay itself is simple, merging two nines can be quite challenging. Once players successfully merge two nines, they can aim to merge two nines again or even go for three nines to achieve higher scores.

The game also features Game Center integration, allowing players to compete for top scores, track the total number of nines made, total points earned, and total nines merged.