I bought a Steam account from Difmark to try Helldivers 2 and see if I liked the game. However, the seller gave me login credentials to a shared account that I can't change the email or password for. They told me I had to play in offline mode—but the game is online multiplayer only, so that's impossible.
When I contacted support, they kept insisting that this was mentioned in the game description—but it wasn't, and still isn’t listed anywhere.
This seems to be a recurring scam they pull, so be careful if you're thinking of buying from them.