So.. while I wanted to log in today to grab the daily reward, I had to find out that it did not want to log me in automaticaly.
I get the "Connect Steam - Use existing Account"-Window.
The first option just lets me pick a name (where my name is already taken. Probably by my own account), and with the second name I can enter a mail/password.
Since I never registered and only linked my steam-account to begin with, I just tried around with some of my Mail-Adresses and Passwords, but to no avail.
The password recovery also did not work.

What happened?