Yes, and as mentioned the IRS decided including V-Bucks/Robux as an example was wrong and posted a correction.
If you somehow made $100k off V-Bucks then you need to report that income, but you should say "No" to the question about digital currencies.
(Disclaimer: I can't believe I have to say this, but if you are making significant money off of video game currencies you should talk to a professional rather than listening to an anonymous HN poster as your sole tax advice)
Additionally, I think that your definition of "digital currencies" is little bit strict. IRS isn't going to look definitions, that exclude taxable income. User semiquaver already posted snippet from "Bloomberg Tax", showing potential interest for gaming currencies.