That’s the neat part, you don’t need an account ! I designed the whole game with this idea in mind. The only thing that’s used to “track” user’s progression is the scoreboard, which is totally optional (but I find it pretty neat, and I hope people will use it ^^).

And even in the case of the scoreboard, no account is needed, upon submitting your first flag, you get to pick your username (3 char, displayed on the board), and receive a cryptographic token that will be asked for to submit the next flag. The token is used to find back your username and update your score. New tokens are generated for each flag.