Oh boy, registration. The good news: registration is free, the bad: it is mandatory. As You are offering Atheios to others, we want to know a bit about You. And You can according to GPDR remove Your account anytime.

This can be Your email address, but maybe better to have an individual id, as this might come up in statistics on our site and visible to other game developers
We'll never share your email with anyone else. You will receive an email to confirm Your address and to finish registration.
Make it a secure one, as this allows You to get access to Your funds and game related assets.
Optional: If You do not have yet a Atheios blockchain account, keep this one empty. You can always change it at a later stage and we will provide an intermediate address in the meantime. If You want to generate Your own address now You can do i here: Web wallet
The nickname is the name being displayed in games or on leaderboards