Panic playing FIFA12 on iMac Mojave

Gulp, all points to Hard Drive corruption or failing.

You can try Disk Utility's Disk First Aid, but doubtful on that working.

Hopefully you have good backups.

You can use Drive DX to possibly get a better view of Drive health…

https://binaryfruit.com/drivedx

Apparently.

Oh, it did seem to indicate your boot drive.

Best of luck my friend.the reason I said apparently, is that it could be the internal cable.