How to Play
Tap the board to open game mode. Then choose a color from the palette beneath the board; tapping individual cells does not make a move.
The connected region starts in the top-left corner. A color choice recolors that entire region and absorbs matching cells connected along their sides. Diagonals do not connect.
Fill every cell before you use all the allowed moves. The Moves panel shows moves used / move limit. Winning on the last allowed move counts.
Difficulty and Controls
Easy: 10×10 board, 4 colors. Medium: 15×15, 5 colors. Hard: 20×20, 6 colors. Expert: 25×25, 7 colors. Start with Easy to learn how connected groups expand.
Each new board is random. The move limit is based on a computer-generated sequence with extra allowance for the selected difficulty; it is not a published minimum number of moves.
Undo restores your last color choice once. Exit leaves the board ready to resume using Back to game. Start new game creates a different random board. After a loss, Retry Board repeats the original puzzle, while Remix creates a new one.
Time counts time spent playing, starting with your first color choice. Best is saved per difficulty: fastest win, or highest filled percentage before a first win. A reload does not restore the unfinished board.
Flood Fill Strategy
Compare the colors touching the edge of your flooded region. A large immediate gain can help, but a smaller move may open a route to several larger groups on your next turn.
A color with no matching cells along the frontier still costs a move. Before picking it, check what it would achieve. You can use Undo to revisit your most recent choice.
Look for disconnected pockets and the color sequence needed to reach them. A rare color may still be necessary to finish; choosing the largest group every time is not a guarantee of the fewest moves.
A small example
Letters stand for four different colors. Start at A in the top-left corner.
A B B
C B D
C D D
Choose B: the region grows from 1 to 4 cells. Choose C: it grows to 6. Choose D: all 9 cells are filled. A matching color joins only when it is connected to the growing region.
This example explains the rules on a small grid; playable boards start at 10×10.
A Color Puzzle, Played in Your Browser
This is the playable Flood Fill puzzle, rather than a programming tutorial about the flood fill algorithm. Plan color sequences, try the same board again, or take a short break with a new random puzzle.
The game is free with no ads, account or download. On your phone, game mode brings the board, palette, statistics and controls together on one screen.
FAQ
What is Flood Fill?
Flood Fill is a color puzzle: choose colors to grow a connected region from the top-left corner until the entire board is one color.
Do diagonal cells join the flood?
No. Cells connect only along their sides. A matching cell touching just a corner stays outside the region.
What counts as a move?
Choosing a different palette color uses one move, even if it adds no cells. The current color is disabled and does not use a move.
Can I undo a color choice?
Yes. Undo reverses your most recent move once, restoring the board and move count. It does not rewind the time spent playing.
What happens at the move limit?
Filling the board on your last allowed move still wins. Otherwise the game ends when the limit is reached. Retry Board starts the same puzzle again; Remix generates a new one.
How do the difficulties differ?
Easy has a 10×10 board and 4 colors, Medium 15×15 and 5, Hard 20×20 and 6, and Expert 25×25 and 7. Higher profiles also give less margin in the move limit.
Does Flood Fill save my progress?
Your difficulty and best result are saved in this browser. Exit and Back to game keep the current board while the page stays open. Reloading starts a new board.
What does Best show?
For each difficulty, Best shows your fastest winning time. Before your first win, it can show the highest filled percentage reached when a game ends at the move limit.
Is this Flood Fill game free and ad-free?
Yes. You can play in your browser without ads, payment, an account or an app download.