All three are games about completing a line, and all three have been solved by computer. The difference is who controls the pieces. In tic-tac-toe and Connect Four each player owns a mark or colour and chooses their own move. In Quarto the 16 pieces are shared, any four with a common trait make a line, and your opponent chooses the piece you have to place. With perfect play tic-tac-toe and Quarto are draws, and Connect Four is a win for the first player.
About us: we make Quads, an independent game built on the same hand-your-opponent-the-piece mechanic as Quarto. It isn't affiliated with Gigamic or the makers of Quarto.
Side by side
| Tic-tac-toe | Connect Four | Quarto | |
|---|---|---|---|
| Board | 3×3 | 7 columns × 6 rows | 4×4 |
| Pieces | X and O, as many as needed | 21 discs per player | 16 shared pieces, all different |
| Who owns them | Each player has a mark | Each player has a colour | Nobody |
| Where you can play | Any empty square | The lowest free space in a column | Any empty square |
| Who picks the piece | You | You | Your opponent |
| Line to win | 3 of your mark | 4 of your colour | 4 pieces sharing any one trait |
| Winning lines | 8 | 69 | 10, or 19 with 2×2 squares |
| Longest game | 9 moves | 42 moves | 16 placements |
| Perfect play | Draw | First player wins | Draw |
Tic-tac-toe
Two players take turns marking a 3×3 grid, and three in a row wins. There are eight lines: three rows, three columns and two diagonals. The game is small enough that most people work out how never to lose, after which every game is a draw. It is useful as a first strategy game for young children and as the standard example of a solved game.
Connect Four
The grid has seven columns and six rows, and it stands upright. A disc falls to the lowest free space in its column, so you can only play on top of what is already there. That restriction is the whole game: a square you need may not be playable until the one beneath it is filled.
There are 69 possible lines of four: 24 horizontal, 21 vertical and 24 diagonal. Connect Four was solved in 1988, independently by James D. Allen and Victor Allis. The first player can force a win by starting in the middle column and playing correctly from there.
Quarto
Quarto is played on a 4×4 board with 16 pieces. Each piece is tall or short, dark or light, round or square, and solid or hollow, and no two are alike. A line is four pieces that share at least one of those traits, in any row, column or diagonal. That gives ten lines. An optional advanced rule also counts the nine 2×2 squares, for 19 winning shapes. Quads uses that rule as standard.
Two things set it apart from the other two games:
- The pieces are shared. There is no "your" line. Whoever places the fourth matching piece wins it, whoever placed the first three.
- Your opponent picks your piece. A turn is two steps: place the piece you were handed, then choose a piece for your opponent. You lose by handing over a piece that completes a line.
Classic Quarto was solved in 1998 by Luc Goossens, and the result is a draw with perfect play. We looked at how the 2×2-square rule changes that in Is Quarto solved?
How the thinking differs
In tic-tac-toe and Connect Four you look for a move that helps you and check that it does not help your opponent. In Quarto you do that twice per turn, once for the square and once for the piece. A position can look safe and still be lost because every piece left in the tray completes something.
The other difference is what a threat is. In Connect Four a threat belongs to one player. In Quarto a line of three matching pieces is a threat to whoever is about to be handed a piece, which may be you. Good players count how many remaining pieces would finish each open line before they choose one. The strategy guide covers this with examples.
Which should you play?
- Ages 4 to 6: tic-tac-toe, to learn turns and lines.
- Ages 6 and up: Connect Four. The rules take a minute and games are quick.
- Ages 8 and up, and adults: Quarto. Recognising shared traits takes a little practice, and it stays interesting much longer.
These ages are a rough guide. Children who already sort objects by colour and shape often manage Quarto earlier, and the classroom guide has activities for ages 7 and up.
Frequently asked questions
Is Quarto like Connect Four?
Both are about four in a row, but Quarto pieces are shared between the players, a line is any four pieces with one trait in common, and your opponent chooses the piece you place. Connect Four has gravity and each player owns a colour.
Is Connect Four solved?
Yes. It was solved in 1988, independently by James D. Allen and Victor Allis. The first player wins with perfect play by starting in the middle column.
Is Quarto solved?
Yes. Luc Goossens solved classic Quarto by computer in 1998. With perfect play from both sides the game is a draw.
How many ways are there to win in Quarto?
Ten lines in the classic rules: four rows, four columns and two diagonals. Counting the nine 2x2 squares as well, as the advanced variant and Quads do, there are 19 winning shapes.
How many winning lines are there in Connect Four?
69 on the standard 7 by 6 grid: 24 horizontal, 21 vertical and 24 diagonal.