If you play this game with all possible difficulty settings quite often it will happen, that one or two characters will die throughout play.
As of now you don't have any mechanic for removing a character from play, after you pushed the start button the scripts that automatically distribute player mats and power decks etc are stopped, so you have to manually put all things of the dead character away and set up a new one.

Also, if during the character choosing phase (hence, before you would press the start button) you should happen to not only look at the starting power cards, but also draw some of your normal power cards to look at them, but then decide to draw a new hero it breaks the previously chosen one, because the drawn power cards will not be returned to their deck, but sometimes rather moved by a certain xyz, at other times they disappear, but that might also be because they were moved and just disappeared into a bag or something. If you or someone else should draw that hero again you will notice that the cards you had previously drawn are now missing from their power deck.

To prevent this, you could just adress all character cards individually, always make [GUID power card #1]...[GUID power card #4] form the starting power deck at location xyz, analogousely with card 6...10 for the power deck at location xyz and then move these two and the figurine back to their container (I might be wrong about this, but I think right now you are just looking at what is on that players specific mat and then move those cards, if a card lies outside of a players mat it just stays there when he's put away by the script). if you always adress all cards individually it should never break anything in any way, me thinks.

(Something else I noticed is, if by accident you should move the figurine of an already chosen character, onto a player mat (with or without a character on it), it will break that player mat, no further figurines are detected by it. This is probably a bug.)

If you would implement it this way, you could also leave the script running after the start button was pressed, maybe add a dump area or something where you can drag a figurine and then the character gets put away, activating its player mat area for the detection of figurines again. (or maybe add a 'lock-button' next to each player mat? so as long as it's locked, nothing happens if a new figurine would be drawn there, but if it's unlocked the old character get's put away and replaced with the new one?)
It would be great to see these changes make it into the game, they would be a big help and add a lot of convenience.

Thanks in advance (:

(p.s.: also, please remove the green back from the keys, they are not a green backed item, they are a unique class of items)