Player Gizmo was short on time. Player Widget was behind in material. As Player Gizmo pushed for the win with very little time on his clock, Player Widget made an illegal move by moving his "checked king" to a square where it was still in check.
Player Gizmo told the player that it was illegal and moved Player Widget's king back to it's original square, then hit his clock. In effect, moving his opponent's piece on his own time!
Player Widget then moved his king to a different square that was also an attacked square, so he was still in check!
The first sequence was again repeated, and in another move or two, Player Gizmo's clock fell, giving Player Widget the win. Of course Player Gizmo was not so sure this was "the rules" and he should be awarded the win due to the illegal moves burning time on his clock.
Unbiased discussion by players standing close to that board concluded that "when the flag falls, its over," and Player Gizmo's only recourse was to immediately hit his clock and inform his opponent that his move was illegal. If it persisted, then stop the clock, and ask for a ruling.
Well here are the FIDE rules that cover this very situation. Player Gizmo has a case!
- If a player displaces one or more pieces, he shall reestablish the correct position on his own time. If necessary the opponent has the right to restart the player's clock without making a move in order to make sure the player reestablishes the correct position on his own time.
- If during a game it is found that an illegal move has been made, or that pieces have been displaced from their squares, the position before the irregularity shall be reinstated. If the position immediately before the irregularity cannot be identified the game shall continue from the last identifiable position prior to the irregularity. The clocks shall be adjusted according to Article 6.13 and, in the case of an illegal move, Article 4.3 applies to the move replacing the illegal move. The game shall then continue.
- A “quickplay finish” is the last phase of a game, when all the remaining moves must be made in a limited time.
- If the player has less than two minutes left on his clock, he may claim a draw before his flag falls. He shall stop the clocks and summon the arbiter.
- If the arbiter is satisfied the opponent is making no effort to win the game by normal means, or that it is not possible to win by normal means, then he shall declare the game drawn. Otherwise he shall postpone his decision.
- If the arbiter postpones his decision, the opponent may be awarded two extra minutes thinking time and the game shall continue in the presence of the arbiter.
- Having postponed his decision, the arbiter may subsequently declare the game drawn, even after a flag has fallen.
- Illegal moves do not necessarily lose. After the action taken under Article 7.4, for a first illegal move by a player the arbiter shall give two minutes extra time to his opponent; for a second illegal move by the same player the arbiter shall give another two minutes extra time to his opponent; for a third illegal move by the same player, the arbiter shall declare the game lost by the player who played incorrectly..
- If both flags have fallen and it is impossible to establish which flag fell first the game is drawn.