res-o-matic probably changed the in-game resolution and unity decided to save it in playerprefs config.
I could suggest you a solution:
Try to delete the game via windows control panel in order to delete the playerprefs config, but it will also erase your save probably, or just delete the playerprefs config, its located in the windows register:
HKEY_CURRENT_USER/SOFTWARE/Unity/UnityEditor
if it didnt help you at all, then Ill probably need to add a resolution change option in the settings, my bad!