After putting in my username and password, I get stuck on the Loading Game page. Username is johnpowell6
You need to open a private(Firefox) or incognito (Chrome) window , go to dominion.games, enter your Name and Password, but don't click "Login". Instead, click on "Kick and Resign" (rightmost of 3 buttons below the login data area). Then you should be able to login normally (no need for private/incognito tab).
Given how often this question and reply crops up, it might be a good idea for the Loading Game page to include the text "If this page hangs, open a private (Firefox) or incognito (Chrome) window, go to dominion.games, enter your Name and Password, but don't click 'Login'. Instead, click on 'Kick and Resign' (rightmost of 3 buttons below the login data area). Then you should be able to login normally (no need for private/incognito tab)."
Thanks, I figured it out myself last night.