Mahjong Stack is a timed three-dimensional sorting and tile-matching game that features Chinese Mahjong and other tiles. Across levels, the player's goal is to use FreeCell and Match-3 moves to clear green tabletops of piles of tiles before they run out of time. They also attempt to earn high scores and use various methods to collect the most coins and stars.
At the start of a level, the game drops a stack of tiles onto the table above seven dark green tile-shaped spaces. The pieces come to rest in a non-uniform pile in realistic face-down, face-up, side, and angled positions. In the upper-center area of the screen, a timer starts to count down.
When the player selects a set of three matching tiles, the game auto-transfers each one to a dark green space and then removes the set from the screen. If they select a non-matching tile, the piece still auto-transfers to a space. The player must then find and select two matching ones. As long as their actions create a match-3 set that frees up new spaces, they can use all seven spaces without a penalty.
Mahjong Stack helps the player with five boosters (i.e., shuffle, flip card, undo, back and add time). For example, shuffle rearranges the stack to reveal tile face icons. The player can pay for these tools with their gold coins or ad views. They can also sometimes collect boosters as rewards.
The player receives double extra coins and rainbow multipliers with ad views. On the home screen, they can also open level and star chests, a separate lucky chest and collect rewards from daily challenges and achievement quests.
