Coins/tokens prohibited from being offered to US investors

[irukandji]

Some coins/tokens are not allowed to be offered to US investors. For example Polybius.

What are some previous coins that were not allowed to be bought by/offered to  US investors?

Are they subsequently able to trade on US exchanges like Poloniex, Bittrex or Kraken?

[ArticMine]

Strictly speaking any token that does not qualify as a Decentralized Virtual Currency under the following guidance first published in 2013 https://www.fincen.gov/sites/default/files/shared/FIN-2013-G001.pdf and where the issuer of the Centralized Virtual Currency has not registered as an MSB with FinCEN.

This leaves tokens with no premine such as Bitcoin, Litecoin, Monero etc. Ripple is the only Centralized Virtual Currency that to my knowledge has made peace with FinCEN.