I have read about this variant in the context of weiqi, however, I cannot find anything about it online. It's something about placing a combination of up to four stones as one move, but what about this "加一"？
I believe it has something to do with Omino Go (Teromino Go?), but I do not see anything about this game (apart from English wikipedia) either.
If you know the rules of the game or a source where I can find out more about it, please, assist