Flow Free

Flow Free, which can also be called "Flow", is a single-player puzzle game available for iOS, Android & Windows Phone developed and published by Big Duck Games LLC. It was originally released on iOS on June 7, 2012. The game was shortly ported to the Windows Mobile platform and an Android version was released on June 29. It features a wide variety of packs that may include bridges, hexes and warps.

Gameplay
The player can draw a flow by running their finger from one dot to the next, starting at either of the colored dots. The flow will be built following through the squares they touch, and a colored glow will track their progress under their finger and brighten when they hit the corresponding dot, completing the flow. If the players runs through a square that is already filled, either by their current flow or another color's flow, the flow that was there will be truncated at that point and overwritten by their current flow. Due to this, it's not technically possible to overlap flows, but they can "paint themselves into a corner" by leaving themselves with no way to progress a flow without breaking another one. They will also break a flow by touching anywhere on it. When they break a flow, it breaks up to the point they touched and will start from the dot that the flow originally began. This is useful for replotting flows differently, as they can start right from the problem area leaving what came before intact.

Connecting one dot to its pair counts as a move, but the move is counted from the moment the player starts drawing the flow. Once they've started a flow they can take their finger off and look around the board or start on another flow, only being charged one move for that color. However, if they touch their flow again after connecting it, another move will be counted against them. The minimum amount of moves is the number of colored pairs, meaning only connecting each pair of dots once. The player can still solve the puzzle with more than the optimal moves, but their finish will be marked with a checkmark instead of a star. They can come back and redo the puzzle at any time to upgrade their completion to a star.

Display
The puzzle area is presented as a square grid made up of rows and columns of smaller squares. Inside the grid, some squares will be filled with colored dots, which are the ends of the flows the player must make. Around the grid is information on the current puzzle and buttons with various functions. At the top of the screen is a back button on the left taking them out to the puzzle select screen, where they can jump to another puzzle or swipe over to puzzles of a different grid size. Next to the top back button is the current level they are on and the size of the current grid. On the right is their completion status, either blank if they haven't completed the puzzle, a checkmark if they've completed it with more than optimal moves, or a star if they've completed the puzzle with the minimum amount of moves.

Below the top line of information is the number of flows the player has made out of the total number of flows, the number of moves counted against them so far and their best amount of moves, and the percent of the grid they've filled in. At the bottom of the puzzle grid are backward and forward buttons that take the player to the previous and next puzzles, and between them is a restart button that will clear the grid and their moves, but not their best moves so far. Depending on how they finish the puzzle—either creating all flows without filling all squares, filling all squares with over the minimum moves, or finishing with a star—they will get options to move onto the next puzzle or keep trying.

Expansions
Big Duck Games LLC has also released three expansions in the series. The first expansion, "Flow Free: Bridges", was released on November 8, 2012, at a fixed price. In this expansion, pipes can be made to intersect through pre-made bridges. The second expansion, "Flow Free: Hexes", was released on October 12, 2016, and features both free and paid premium puzzles. The gameplay is similar to "Flow Free" except the layout resembles hexagons instead of squares. The third expansion, "Flow Free: Warps", was released on August 8, 2017. This expansion allows the player to have pipes warp from the edge of the map to the other edge of the map.