Sharing an Old Save File , All Campaigns Cleared, Most Units Unlocked

Is there a way to reset the game progress?

Corrupted Save file ?

Are there any mods to unlock all units?

Is the game playable now?

I keep getting era messages and the game will only let me go so far even though completed the missions

And play again from the beginning.

Cant progress in campaign

Scale

The game does not complete the mission