No account
DIGIGMA does not ask you to sign up. There is no password and no profile. You open a board and play.
Play is local. Continue and Solved belong to this browser. Another browser on the same machine is a separate place. Another machine is a separate place.
That is the point. You sit with a board. You do not perform for anyone. You do not publish a result.
If you want to keep a puzzle, leave it unfinished and use Continue on Home, or finish it and find it on Solved. That is all the site stores for you.