I signed up when it was new. It used to be you got a 'ship' which was a 12 char string that was essentially your IP/DNS/identity. Then later they changed it to 'planets' and you had to re-register again.

Then they moved it all to Ethereum in 2018 but I had stopped giving a shit so I don't know what happened after that.

I should also note they did an auction of address space prior to Ethereum, seemed like they were trying to get in on the crypto grifts. It's all completely incomprehensible to me even though I used it for a good year or so lol