Count six occupied spaces, not six pieces of one side
The main board has six rows and seven columns. Every piece in a column contributes to its height, whether it is X or O. A stack containing three Xs and three Os uses all six positions. The next piece cannot pass through them, replace the top piece, or sit in a seventh row outside the board.
A column can become full without producing a winning line. The marks may alternate, and other columns may still be empty. Check the result and available columns separately. “This destination has no space” explains a different situation from “the entire round has ended.”
Build a full column without creating a four-piece vertical
Use the two-player same-device board to alternate X and O into column A six times: X, O, X, O, X, O from bottom to top. There are three pieces of each side and no four consecutive matching pieces in that column. No other column has been used, and it is X’s turn again.
Trying A once more does not create a legal seventh piece. An input aimed at the full column cannot manufacture another row or remove one of the existing marks. This constructed exercise uses human control of both sides so that you can reproduce the alternating stack without assuming the main computer chooses a cooperative sequence.
Distinguish an unavailable destination from a frozen game
Inspect another column. In the example, B through G still have room, so the position is not drawn merely because A is full. A legal choice elsewhere places one piece in that column’s lowest open space. The column you first considered remains full; waiting or repeatedly selecting it does not free a slot.
On a phone, confirm which column control you are using. A tap near a neighboring column can create a different legal move from the one you intended, while a correctly selected full column remains unavailable. With a keyboard, focus identifies navigation, not an exception to capacity. Read the stack and the control’s current state rather than treating every unchanged view as a loading problem.
A finished round creates another kind of restriction
Four consecutive matching pieces end the round even if many columns still have room. After that, an empty space does not grant another defensive turn. If all 42 board spaces are occupied without a winning line, the result is a draw and no column remains available.
Keep those cases separate from the alternating six-piece example. A full stack in A does not by itself establish either outcome. When explaining a screenshot, show the rest of the board or state that the other columns are empty. Otherwise a reader cannot tell whether your rejected drop came from column capacity or a result already reached elsewhere.
Start over only when that is the action you want
A confirmed reset or New game replaces the position; it is not a way to delete just the top piece of the full column. Pause preserves a different intention when you want to return to the same problem. Read the confirmation before clearing a stack you meant to discuss.
The exercise is stored locally when the browser allows and retains the game’s data. It is not a synchronized online room or a message to another player. To test a different stack, recreate the legal alternating turns on the shared board rather than adding hypothetical pieces outside its six rows. Understanding the capacity limit gives a precise next step: inspect the round’s result, choose an actually open column if play continues, and analyze the landing square that move will really reach.
Frequently asked questions
How many pieces fit in one column?
Six, regardless of which side owns them.
Does one full column mean a draw?
No. Other columns may still be open, and the result must be checked across the board.
Can I add a piece above the sixth row?
No. There is no legal seventh row or floating destination above the grid.
Can an empty column reject play too?
If the round already ended with a winning line, empty space does not authorize another move.
Does Reset remove only the last piece?
No. A confirmed reset replaces the game state rather than selectively opening a full column.