After reading about all the latest goings-on, I'm inclined to believe that this token here is one of the hottest properties in the world of crypto as of right now
Yes you can buy Tagcoin on Russian Yobit exchange
...and also Nova exchange if you're not in the US.
BTC to TAG https://novaexchange.com/market/BTC_TAG/
DOGE to TAG https://novaexchange.com/market/DOGE_TAG/
Nova is definitely on the correct block chain, I can't ascertain what block-chain Yobit is on.
Join the Discord Discussion over at https://discord.gg/VfuGYZH
The Tagcoin both on Novaexchange, Yobit as well as the old AEX(not sure what's it called nowadays) are trading the OLD TagCoin and can't be used on the Tagcash platform, so other then trading and speculating it has no value.
As already has been written about, TagCoin has moved to the Stellar Network. The old Tagcoin can still be swapped for the new TagCoin, though. Just have to contact Tagcash and talk to them.
Tagcash is developing module after module for their app and web application, with still a few very exiting services rolling out soon. Of course TagCoin will be used to pay in these modules. Hopefully this will clarify again the differences.