Over the years, it's easy to misplace that booklet of rules that comes with every board game. If you remember the rules, at least well enough to convince your friends and family to play, that may not be a problem. But if you've picked up a used game from somewhere or you've forgotten some important details, a copy of the rules will come in handy.
Hasbro offers a list of more than 70,000 game rules and instructions on its customer service site — and from a look through the list, I don't think they're all actually Hasbro games.
There's another reason that this resource is a treasure trove of sorts: for the board game designer, have access to the rules governing thousands of rules can provide inspiration, guidance, and probably at least a few examples of what not to do!
Very impressive archive of game rules. Thanks for the entry.