wikipedia :
The game has three modes:
One Duck – In each round, there are 10 ducks for the player to shoot down. Only one duck appears on screen at a time, and the player has three shots to hit it.[8]
Two Ducks – Identical to "One Duck" except that the ducks appear on screen in pairs. A new pair of ducks will not appear until both of the previous pair have either escaped or been shot down.[8]
Clay Shooting – In each round, there are 10 clay pigeons for the player to shoot down. Clay pigeons are fired off two at a time from a first person perspective and are aimed into the distance.[8] In Vs. Duck Hunt, Clay Shooting mode appears as the second round with the first round being the two duck variation (the arcade version never had one duck).
