Welcome to the Dungeon — initially released as Dungeon of Mandom — is a push-your-luck dungeon delve in which 2-4 players take turns essentially daring each other to go into a dungeon with less equipment than they start off with while filling the dungeon with monsters. Players win the game by winning 2 rounds or get eliminated from the game by losing 2 rounds. Every player has a 2-sided players card that has a white side and a red side. The first win taps the player card and the 1st loss flips the card over to the side that's red. A 2nd loss will have the player toss the card back into the box.

This game is played in rounds. The player sets up the base character and all the equipment equipped. This represents every player as a fully equipped dungeon delver.

Each round, the start player (the person who challenged the dungeon last or the last player to be in a dungeon) can choose to take a card from the monster deck or pass their turn.

If they choose to take a card, they can do one of two things: (1) keep it and de-equip an equipment or (2) place it face down in the dungeon. Placing it face down in the dungeon creates the dungeon deck and fills the dungeon with monsters that the challenger must face later. If players choose to pass their turn, they cannot participate in the rest of the round. Once only one person is left after all the other players have passed their turn, that player then becomes the challenger and must go into the dungeon with only the equipment they have equipped.

The player then flips cards off the dungeon deck and battles the monsters within. Some equipment allow you to nullify the enemy damage or be able to withstand it by increasing your HP. If the player comes out of the dungeon with at least 1 HP, they win that round. If they don't, they lose. Players then reshuffles all the cards to make a new monster deck and re-equips all the equipment to start a new round.

The game is over when someone has won twice or one player is the last man standing.

Welcome to the Dungeon comes with four different sets of character cards whereas Dungeon of Mandom has only a single character.