Board Game Arena

It will be helpful if someone can elaborate when can a player undo their moves and when they cannot?
So far it seems it is a hit or miss with undoing their moves

Yes, this is a fine point.

The latest rules v1.3 available on BGG (https://boardgamegeek.com/filepage/1371 ... -rules-v13) say for actions 1 an 7 "You may not play a 7 if you cannot stay in the game at the end of your turn." and "You may not play a 1 if you cannot stay in the game at the end of your turn."

That's the rule applied on BGA, as visible in the tooltips on cards 1 and 7.

So if the player puts himself in this forbidden situation, the possibility to undo the full turn is provided (and mandatory) otherwise the player would not be able to respect the rule.