I had always heard that it is forbidden on Shabbat to do any sorting (put all the spoons together, all the forks) as this is a form of borer. In looking into it, I couldn’t find any sources for this older than the early 20th century…Is this actually a halachah? Would it make any difference if it is for a game (putting all the red checkers together, etc.)? Have I overlooked something?
Sorting silverware is a form of Borer. Not all sorting is though. See Aruch Hashulchan Siman 319 8-9.
Games may be different because you are always taking the piece that you need (depending on the game). It’s similar taking the “good” from the “bad” which is permitted.
Can you explain why sorting silverware is Borer?
I am neither taking bad from good nor good from bad - just putting away forks, knives and spoons.
It doesn’t need to be good and bad. Just two “species” combined.