Blockchain games as a topic can have a scope that exceeds NFTs: previous implementations using regular old tokens are fine too, or alternatively with a new altcoin.
I guess. But outside of the likes of gambling, having NFTs in "blockchain games" is pretty much the norm now. You're very unlikely to see a blockchain game that only operates using tokens and without the use of NFTs.
Yes, it's a mix of token (altcoin) and NFTs (game's items/characters).
Moreover I believe the main difference between blockchain games' NFTs and other NFTs is the practical application the first have, against a worthless existence of the second (like most altcoins). And since there is practical application, this segment of the market doesn't rely purely on speculation (unlikely altcoins). Also, games' NFTs are similar to products/goods instead of currencies. These are some reasons to detach this category from altcoins, which includes worthless NFTs as well.