They probably will ask their parents to pay in XRP if they have heard somewhere that their dads or moms are into cryptocurrencies. Anyway, good news as it is for XRP, and can get the term about accepting crypto for a game since Roblox has hundreds of millions of players.
It's better if they also allow Bitcoin to get accepted into this game and other altcoins that are mostly popular in the market. Since they're partnered up with Bitpay then it's most likely that every cryptocurrency that they support can be used for payments in-game purchases.
As long as we get to understand the context of it as this game accepts now crypto, I guess that's the most important part of this news.