For the first few weeks, your Isotropish ranking will be used to identify a "good match". If you didn't get a message that the username is reserved when you created your account, I assume that your current ranking as .ahisma, will be associated with your new account.
If you haven't visited before, the start rankings are available at
http://gokosalvager.com/leaderboard/?full=True&sortkey=level.
Games are not currently ranked, but rankings are planned to be implemented. I'm not sure whether game logs or results are retained at the moment for use in the coming ranking system. If you want to play without consequence, Lord Rattington is probably the safest option at the moment, but beware that the AI is not yet competitive.
You can also visit the ShuffleIT forums for more information:
http://forum.shuffleit.nl/, or use the ShuffleIT discord server for support or questions:
https://discord.gg/FnWd3KY.