Four in a Row

Four in a Row is a two-player drop game played on an upright board against the computer. Each of you drops discs into columns, and the first to line up four of their own wins. It is easy to learn in a minute and gives you plenty to think about for much longer.

How to play

The board has 7 columns and 6 rows. You play the red discs and the computer plays yellow.

• On a phone or tablet: tap a column. Your disc drops to the lowest free place in that column.
• On a computer: click anywhere on the column you want.

After your move the computer drops a yellow disc. You take turns, and the one who starts changes from game to game.

Four discs of one color in a straight line win: across, up and down, or on a slant in either direction. If all 42 places fill up and nobody has four, the game is a draw.

A line of four can use discs that were dropped many turns apart, so always look at the whole board, not just the last disc.

The levels

The only thing that changes is how well the computer plays.

• Easy: it looks only about two moves ahead, and roughly one move in four it plays a random safe move instead of its best one. Undo is on, so you can take back a move.
• Medium: it looks about four moves ahead and plays steadily. Undo is on.
• Hard: it searches about seven moves deep and does not slip. There is no undo.
• Expert: it searches as deep as its time allows, up to fourteen moves, and takes about a third of a second a move. There is no undo.

Tips

1. Start in the middle column. A disc in the center belongs to more possible lines than a disc at the edge, so it keeps your options open.
2. Look for three discs in a row with free space at both ends. If both ends can be played, the opponent cannot stop you.
3. Before every move, ask what the computer would do if it got your move. If it could win by dropping into that column, you must block it first.
4. Be careful about dropping a disc that gives the opponent the square above it. If that square would let them complete four, you have just handed it to them.
5. Try to make two threats at once. A single threat can always be blocked, but two cannot both be blocked in the same turn.
6. Threats on diagonals are easy to miss because the supporting discs are on different heights. Check each slant before you drop.
7. On Easy and Medium, use Undo to learn, not to avoid thinking. Take back a move, then try to see what the computer was aiming at.

Questions

Who goes first? It changes each game. If the computer goes first, it drops its disc before you can move.

Can I take back a move? On Easy and Medium, yes, with Undo. On Hard and Expert, no.

What if the board fills? Then the game is a draw. Neither side has four.

Does the computer ever cheat? No. It follows the same rules as you and only sees the same board.