Enter The Gungeon

Winchester’s game is a carnival-style shooting game in which the player must use the game’s environment (while avoiding obstacles) to shoot 4 moving targets. Winchester’s game room is random and is not guaranteed to spawn on every run. The room looks like this:

This achievement is earned by acing (shooting all 4 targets) the game 3 times throughout any number of runs. The easiest way to ace Winchester’s game is to either buy or steal an item that allows flight. By flying, you may approach and shoot the moving targets at point-blank range without facing repercussions. The most common items that allow flight are:

+ Wax Wings (will add curse to player if bought from Cursula)
+ Ring of Ethereal Form (this is an active item, so you will not fly permanently - be careful!)
+ Jetpack

While flying is not considered cheating, swapping your weapon to any gun other than the default Winchester’s game gun at any time during the minigame will prevent you from earning rewards for acing the game. I assume this affects the achievement, as well, so don’t swap your gun once the game has begun!

Alternative option: If you are exhausted from waiting for flight-enabling items to show, you can attempt to win the game legitimately. Here are some tips and rules that may help:

It is a game of angles, much like billiards. Shooting a GREEN block will bounce your shot and destroy the block(s) initially impacted. BLUE blocks cannot be destroyed, but will bounce your bullets. RED blocks cannot be destroyed, but will destroy and not deflect your bullets (avoid these!).

If you ace the game 3 times, you will be awarded this achievement and the Seven-Leaf Clover item (better chests) once you have spoken with Winchester in the Breach. Good luck!