I think that'd be a pretty neat mod, I think the Mood System could really work well! But for the Happy moods then there'd have to be a disatvantage other than lower hitrate due to this game not caring lol

Angry moods obvious could give you Vulnerable and/or Fragile while giving you strength and Sad moods could give you Weak or reduced Strength while giving you more Defense

And of course they'd stack which means you could go up to Furious, Miserable and Manic

As other cards maybe cards based off the Equipement you get, also Friend cards based off NPCs and friends and the obvious cards based off Omori's or Omori's friends' Skills!

Overall I think this mod could be interesting, though it could be a bunch of work lol