Personally I think that is a bit of an overstatement. While there is no doubt Witcher 3 did something remarkable there are plenty of other amazing RPG games out there I really enjoy.
Shh, where is your gaming patriotism? I know it's not the best thing ever since the creation of the Universe but hey, our guys did it, and it's awesome.
But Witcher 3 is definitely a thing Poland should be proud of :v Only sometimes I feel like people are VERY overreacting over that game. It is amazing, but throwing it at every other title makes it annoying. It isn't perfect and had its flaws too :v