Hi there.
I just tried downloading "ERA-Linux-8Apr2018.tar.gz" from RPGNow to an Ubuntu 16.04.
If I navigate to the file, right-click on it and choose "Extract Here" it all goes smoothly. Then I can run ./ERA-RMFRP and it all works as expected.
If instead I execute the exact tar command you mentioned I get the error you posted, though hirazi.png is a valid transparent image much like a lot of others in that directory, which you can confirm if you uncompress via the UI.
Checking the issue online,
I found this. There it suggests to add
i as an additional parameter.
So I tried it and it worked. You need to uncompress using:
sudo tar ixzvf ERA-Linux-8Apr2018.tar.gzPlease let us know if that solves the issue.
Thanks for your interest in ERA!