Duck Hunt on the NES vs the Browser Remake: What Changed and What Did Not

Duck Hunt came out in Japan in April 1984 and in North America with the NES launch, bundled with Super Mario Bros. and the grey-then-orange Zapper light gun. The gun did not fire anything at the screen. When you pulled the trigger the game blanked the picture for a frame, then drew a white box where each duck was; the photodiode in the barrel reported whether it was looking at a bright box, and the timing told the console which duck you had hit. It only worked with a CRT television, because a CRT draws the picture in a scanline sweep the gun could time against. On a flat panel there is no sweep, so the original hardware cannot register a hit at all.

What the remake does instead

DuckHunt-JS, the open-source version served on duckhunt.pro, replaces the photodiode with a click. Each shot is a point on the canvas; if a duck's position is within 60 pixels of it, that duck is hit. That is more forgiving than the Zapper, which needed the barrel dead on the duck, and it is why the remake gives you exactly one spare shell per wave rather than the NES game's three shells for one or two ducks.

What stayed

• The scene: the tree on the left, the bush on the right, the grass line the ducks launch from.
• The dog. He sniffs, jumps into the grass, then either holds up your ducks at the end of a wave or pops up laughing when one escapes.
• The duck tally along the bottom: black silhouettes are hits, white ones got away.
• Two duck colors, black and red, with the flapping animation, the hit-and-fall animation and the falling sound.
• The sound: the quack loop, the shot, the laugh, and the level-clear fanfare.

What is different

• Six fixed levels instead of the NES's endless rounds. On the cartridge the game just kept counting up and got faster; the remake ends after level six with a score screen (your points as a percentage of the maximum, graded from "Flawless victory." to "Yikes.") and a Play Again prompt.
• A pass mark of more than 60% of the ducks per level, rather than the NES's fixed number of required hits per round.
• No Clay Shooting mode and no two-player mode. The remake is Game A only.
• A level creator on the C key, which the cartridge never had. It puts the settings into the page address so a custom level can be shared as a link.
• Fullscreen on F and pause on P. The NES had neither.

Why it runs anywhere

The remake is built on PixiJS, which draws with WebGL when the browser has it and with the 2D canvas when it does not. The whole game is one script, one sprite sheet and one sound file, about two megabytes, hosted on this domain. That is why it loads in a couple of seconds on a school Chromebook and does not need a plugin, an account or a download.