Undercroft Deckbuilder Roguelike: How to Play With Friends (1–4 Player Co-op)

Undercroft: Deckbuilder Roguelike is built for company from the ground up. Its creator, the Roblox group NEVER GIVE UP!!!!, describes it on the official game page as a “co-op card roguelike for 1–4 players inspired by Slay The Spire 2.” That line settles the party question: a descent supports one to four players, so you can run it alone or take up to three friends down with you.

Party size vs. the Roblox server cap

Two different numbers circulate around this game, and mixing them up is the main source of confusion about how many friends you can bring:

If you run into 24 attached to Undercroft in Roblox's game data, that is the platform's capacity limit for the experience's servers. The game's own description is what defines co-op here, and it keeps the party at 1–4 players.

What the game says about co-op and a shared descent

The official description frames the loop in a few lines: “Build your deck. Pick your path. Defeat is part of the path.” Alongside the 1–4 player range, it lays out what a party actually descends through together: 5 heroes, a pool of 300+ cards, and 30 bosses guarding the way down. Every descent is different, and every one ends with something waiting at the bottom.

For a group, that means every session is a fresh run rather than a fixed sequence of rooms: the party picks heroes, builds decks from the game's cards, and works its way down toward whatever waits at the bottom. The heroes guide and the deckbuilding guide cover those choices in detail, and the cards list shows what is in the pool.

Leaving, saving and continuing a descent

The description closes with its save rule: “Your descent is saved when you leave. Continue any time.” A descent is therefore not erased because someone closes Roblox — the game states that your run is saved on leaving and can be picked back up whenever you return. Note that the description states this about your descent in general; it does not spell out how saving behaves inside an active multi-player party. The save-progress guide looks at saving in more depth, and the runs guide covers the rest of what a descent involves.