Best way to make an "No Registration required" authentication system?

I'm currently building a provably fair dice system in Laravel and it is near complete, however when looking at most of these sites they offer what they call "No Registration Required", bsaically what you do is you go to their site, enter a username then it prompts the user to enter a password but he can do so "later", I assume this is to let the user try it out their product without any hassle of registration and such.

Here is an example: https://primedice.com/ https://stake.com/

What would be the best way to do this? My direct thought was to make the email and password field not required, have a prompt when the user first visits site and ask for a username, then create the user and return it to their session.

Is there any other way to do this, is there any available examples on this?

Note: I am using laravels authentication system.