DK Bros. 2 Player Co-Op Donkey Kong Prototype (Hack)

I've hacked a 2-player co-op version of Donkey Kong. It maintains all the original gameplay mechanics. 2 players simultaneously work together smashing barrels, collecting items and pulling rivets. I have it working as a prototype across all stages. Here's gameplay from the barrels stage. Each player gets 2 hammers. P1 gets the barrel control. P2 doesn't control but gets the advantage of not being targeted. Pulling rivets is fun with 2 players sharing the task. Reduces some of the difficulty. If one player dies then both players die. If one player completes the stage (barrels, pies, springs) then both players complete the stage together and get the bonus. Both players accrue points independently. There could be other gameplay variants. At the moment it's all co-operative. There could be a competitive mode e.g. first player to finish the stage gets all the bonus points.