500 - Multiplayer card game

500 - Multiplayer card game is an open-source Android game for people who want to play the Australian and New Zealand trick-taking card game 500. It supports newcomers learning the rules as well as players who already know the game and want to play with friends or against computer opponents. The aim is to bid for tricks, choose contracts and trumps, and lead a partnership to 500 points.

The game follows Australian rules with a 43-card deck, including the Joker and both bowers, plus a three-card kitty. Bidding covers six to ten tricks in the suits and no-trumps, and includes Misère and Open Misère contracts. Play formats include four-player partnerships, two-player head-to-head games, and six-player games arranged as two teams of three or three teams of two. A score sheet records each hand's contract and points, with the first side to reach 500 winning the game.

Players can play offline against AI opponents without an account or network connection. Online rooms can be created or joined with a short code, with play available between Android and the web, and empty seats filled by bots. If a player disconnects, a bot plays that hand until the player returns, and the app can be directed to a player’s own server. An interactive tutorial teaches bidding, discarding and trick play through a dealt hand, while completed tricks can remain visible and the pace can be adjusted to help players learn to count cards.

The app includes house-rule settings that can disable Misère or no-trumps bidding. It is free to use, and its source code is available at https://github.com/rotundtapir/500. As an Android title in the Games category, it is distributed through MirrorNest by mirroring the official build directly onto MirrorNest storage. MirrorNest scans that mirrored build for malware before publishing it in the download catalog.