So the itch page was public but we don't think it had a build published, hence why its only really some art and parts of your premise that match up. Not suggesting you would have, but it wouldn't have been possible to replicate any gameplay at the time anyway. We can prove we were working on the project in October, and we can show some striking similarities, but unless itch has the page creation date hidden away anywhere then that's about it.
I'm also not accusing you specifically, unless you're the only dev. Things like this can go under the radar and not everyone is aware of it. That's why I've brought it up in the first place, I wanted to be honest about it and make sure you all were aware, but I'm not here to blame or cause any issues. Its heavy inspiration at most, nothing has been stolen or anything, so no harm done.
This menu screen, or something similar, would have been on the page at the time, as well as a description about an abandoned nuclear facility, etc.