Easy "Biggest Wallet" achievem...
	Easy "Case Closed" achievement...
	Easy "Day Ruiner" achievement...
	Easy "I Knew Someone Would Do ...
	Easy "The Password" achievemen...
	Various Steam Achievements...

You must be holding a total of at least 300 coins. Clear all rooms in each chamber and try not to purchase anything at the shop. If you find the Sell Creep, give him guns and items in return for some coins. You might be able to reach the desired total before completing chamber 3, especially if the secret chamber was cleared. Note: This will also unlock the Coin Crown.

Complete one of the main characters' past to get a very rare random chance to find a Bullet Kin with a red cape replacing a regular Bullet Kin. They will simply wander around and will not shoot at you or deal contact damage either. If the caped Bullet Kin is the last enemy in the room with you, it will eventually disappear. Allow this to happen five times over any number of playthroughs to unlock the Bullet as a playable character.

You will eventually unlock a weapon called "The Mailbox" in the Acquisition's Department. Once obtained, notice that it fires letters, with the last "bullet" being a parcel which can have a variety of effects (poison, explosion, and glitter). Fight the Boss and glitter all over it. If done correctly, the Boss will be sparkling. Then, kill it using another weapon.

Flip a table on its side then push it into a pit.

Green demon faces will rarely appear in rooms, usually on the later floors. If you have either 100 casings (money) or at least one curse from any source altars, cursed guns, stealing, breaking a mirror etc.), enter and to teleport to a market room with every item-selling Gungeon NPC available, including a side room with Winchester and his game. If you do not have 100 casings or a curse, the face will spit you out.

Complete the indicated task to unlock the achievement.

Achievement	How to unlock
Advanced Slayer	Defeat an Advanced Boss.
Beast Master	Complete the game with Beast Mode on.
Beep	Unlock the Robot.
Biggest Wallet	Carry a large amount of money at once.
Cartographer's Assistant	Map the first Five Chambers for the lost adventurer.
Case Closed	Unlock the Bullet.
Castle Crasher	Clear the First Chamber 50 Times.
Challenger	Complete Daisuke's trial.
Day Ruiner	Kill a boss after covering it with glitter.
Deadliest Game	Kill the Hunter's Past.
Demolition Man	Kill a frozen enemy by rolling into it.
Double Jeopardy	Kill the Convict's Past.
Dungeon Diver	Clear the Second Chamber 40 Times.
Exorcist	Kill a Jammed Boss.
Forger	Clear the Fifth Chamber 10 Times.
Going Down	Open the shortcut to the Second Chamber.
Going Downer	Open the shortcut to the Third Chamber.
Going Downest	Open the shortcut to the Fourth Chamber.
Grate Hall	Access the Oubliette.
Great Hall	Populate the Breach.
Gun Game	Complete the game with the Sorceress's Enchanted Gun.
Gungeon Acolyte	Complete the Tutorial.
Gungeon Master	Clear the Sixth Chamber.
Gunsmith	Construct the Bullet that can kill the Past.
Hedge Slinger	Win a wager against the Gunsling King 5 times.
Hero of Gun	Kill the Bullet's Past.
Historian	Complete all 4 main character Pasts.
Hollowed Out	Clear the Fourth Chamber 20 Times.
I Knew Someone Would Do It	Why.
Jammed	You've met with a terrible fate, haven't you.
Last Stop	Open the shortcut to the Fifth Chamber.
Lead God	Collect five Master Rounds in one run.
Lion Leap	Fall at the last second.
Mine Master	Clear the Third Chamber 30 Times.
Money Pit	Kill 100 enemies by dropping chandeliers.
Not Just A Box	Get the jump on a Mimic.
Patron	Spend big at the Acquisitions Department.
Pit Lord	Kill 100 enemies by knocking them into pits.
Rage Mode	Always be flipping. Guns are for flippers.
Re-Armed	Deliver the Golem's replacement arm.
Resourceful	Take Revenge.
Reverence for the Dead	Access the Temple.
Rider	Kill 100 enemies while riding in a mine cart.
Slayer	Defeat the Boss of the Fifth Chamber.
Sledge-Dog	Complete Tonic's Challenge.
Squad Captain	Kill the Marine's Past.
Sworn Gun	Avenge Manuel.
Terminated	Kill the Robot's Past.
The Password	Accessed the Hidden Market.
Time Paradox	Die in the Past.
Trickshot	Ace Winchester's game 3 times.
Weird Tale	Complete Frifle's Challenges.
Wingman	Kill the Pilot's Past.
Woodsie Lord	Steal 10 things.