Hello,
This is a common problem at FOD in the Go room. This is a form of cheating called pass/reject. First off please take a screen shot of the offending player if this ever happens again and report him as a cheater. Now how to stop the issue.
If your opponent marks living stone dead or rejects your accurate marking of stones, you only have one option other than quitting (please don't do that). You should never let the cheater win. What I do is what you call the "suicidal" move. Remembering that in Go if your opponent respond to your move in there territory it does not effect the score. So the "suicidal" move isn't actually suicide. Because your stone which is captured is canceled out by them filling there liberty. Also make sure to count the score for yourself and make sure that the stones being marked dead are actually going to make you lose the game. Some cheaters will just click random stones assuming that you will always reject. If you have 35 captures and 50 points and they only have 25 points plus the few stones they might mark dead. You will likely still win if they mark them dead. Count and make sure the stones marked are actually enough to lose the game.
If you have no more valid moves within your territory that is good. For this to work you can't have any liberties that are not single eyes in your territory. Continue playing filling there territory. Once your opponent passes before you. Consider the game won. When they mark your stones dead. Reject. This will cause you to pass, and them to fill in there territory, because you will have no where in your territory to place a stone. Keep filling there's until it is nothing but single eyes. If they pass first they will have to fill there eyes. Allowing you to take there stones. Continue doing this. Until there are no more valid move for them to make. If you capture a large group of stones fill your territory and make it all single eyes. Once the board is filled with your stones and your opponent runs out of moves and has no stones on he board. The game will end automatically upon both players passing. There will be no marking of stones since there are no stones to mark.
Also do not pass. until your territory is filled with single eyes. That parts important. For some reason if you both pass to many times, and it is continually rejected. The game will automatically end in a draw.
I know this may sound confusing, for any one who would actually like to see how to do this please find me @ Go Room 1 and I will happily go to unrated and show you how to defeat a cheater.
KBAD out.... ~
