This inspires me
Movie Adaptation $2 Action - Retcon
Unplay each Action you played this turn, in any order.
Shuffle the unused Ways, and reveal the top two Ways. For each Action this card unplayed, play the Action as one of those Ways.
Inconsistent Narrative $3 Treasure - Retcon
Unplay an Action, then play an Action or Treasure from your hand twice.
To unplay a card, "simply" unplay its effects and return the card to your hand.
Unplaying Vanilla effects:
+1 Card ... Put a card from your hand onto your deck
+1 Action ... If you have extra Actions, -1 Action; otherwise unplay another Action card you have in play
+$1 ... take a Debt
+1 Buy ... If you have extra Buys, -1 Buy; otherwise return a card you gained in this Buy phase to the Supply.
There's some clear loopholes in there lol
Unplaying non-Vanilla effects:
gooooood luck