[glassjester]

Would it be possible to modify Duck Hunt for NES so that it has a 2 player competitive mode, with 2 zappers being used at once? I know nothing about rom hacking, but if this is even theoretically possible (given the hardware), then it I think it would be worth learning.

[Dr. Floppy]

This might not be feasible due to the inability of the NES to determine which gun fired which shot.

[glassjester]

In Chiller for NES, you could use 2 zappers at once, and it kept score separately for each player. So it definitely could tell which zapper had actually hit the target.
March 08, 2015, 05:05:50 pm - (Auto Merged - Double Posts are not allowed before 7 days.)Actually, this would be a very fun feature for Wild Gunman, too.

[Dr. Floppy]

In that case, then yes: it would be possible to make Duck Hunt 2-player competitive.

[glassjester]

Ok, so where do I start? What should I read/watch/download to make this idea feasible?

[Dr. Floppy]

Ok, so where do I start? What should I read/watch/download to make this idea feasible?

This will be your home for the next few weeks: http://wiki.nesdev.com/w/index.php/Zapper

Moreover, I'd highly recommend analyzing the piss out of the Chiller ROM, specifically those sections pertaining to the $4016/$4017 registers.

[KingMike]

Never played Chiller but I have watched Pat the NES Punk play it two-player with his pal Ian.
And I do recall the 2P Zapper mode being glitchy as hell. Which is probably why no licensed game used two Zappers.
(if I remember, it was something like the NES can only read one Zapper at a time, so if both players shoot at the same time, only the player who shot first counts and the other will be ignored)
Which would make sense if I understand how the Zapper reads targets: it not being able to distinguish individual targets, so when the trigger is pulled games have to blank the screen and check each sprite one at a time (and as such one frame at a time) to figure out which one the gun sensed)

[mrrichard999]

This might not be feasible due to the inability of the NES to determine which gun fired which shot.

Who shot first, Han or Greedo

[Dr. Floppy]

Who shot first, Han or Greedo

Originally, or after Lucas "remastered" the scene with neon walkie talkies?

[glassjester]

players shoot at the same time, only the player who shot first counts and the other will be ignored)

Which would be fine (ideal, even) if you're both competing to shoot the same duck.