He might say that, but I think "language-game" is not quite the right take.
Anyways, to shore up my impression I looked up "Schopenhauer eastern philosophy" and hit a few things. The "Schopenhauer and Buddhism" piece by Peter Abelson
( at http://ccbs.ntu.edu.tw/FULLTEXT/JR-PHIL/peter2.htm ) seems good:
"When the tenets of Buddhism became known in
Europe during the third and fourth decade of the
nineteenth century, Arthur Schopenhauer was
delighted with the affinity they showed to his own
philosophy. Having completed his main work Die Welt
als Wille und Vorstellung as early as 1818, he
considered it an entirely new (and thus pure)
expression of the wisdom once taught by the
Buddha."
I would have been gladder if the original article, by a professional philosopher, which I am not, had said something about this.
