# Playcards

> Mau-Mau, Schlafmütze, Blackjack, Skat and Doppelkopf vs the computer, at home or online. Playcards is a card table for five classic games: Mau-Mau, the quartet race Schlafmütze, Blackjack with play money, Skat by the International Skat Order and Doppelkopf by the DDV tournament rules. Play against computer players in three levels, pass one device around with a privacy screen, or invite friends to an online table with a six-character code. Every game has its own rules page, tutorial, house rules and statistics.

Playcards (Card games table) is an app of usefulweb.app (https://usefulweb.app/): a full program that runs in the browser. Its engine is deterministic and the same functions are exposed as tools, so an agent can compute exactly what the app shows.

## Use it
- Landing page: https://playcards.usefulweb.app/
- Workspace (browser app): https://playcards.usefulweb.app/app - open a project with https://playcards.usefulweb.app/app#project=<base64url-encoded project JSON> or a template with https://playcards.usefulweb.app/app#template=<id>
- Project file format (JSON Schema): https://playcards.usefulweb.app/project.schema.json
- Tutorials: https://playcards.usefulweb.app/tutorials
- JSON API: POST https://playcards.usefulweb.app/api/v1/tools/<toolId>/calculate (catalog: https://playcards.usefulweb.app/api/v1/tools)
- OpenAPI: https://playcards.usefulweb.app/openapi.json
- MCP (Streamable HTTP): https://playcards.usefulweb.app/mcp

## Engine tools
- [Skat Game Value Calculator](https://playcardsskatgamevalue.usefulweb.app/): Skat game value from contract, matadors, Hand, Schneider, Schwarz and Ouvert — with overbid check. Part of [Playcards](https://playcards.usefulweb.app/) (ownerApp: playcards). API: POST https://playcards.usefulweb.app/api/v1/tools/playcards-skat-game-value/calculate · MCP tool `playcards_skat_game_value`
- [Doppelkopf Score Calculator](https://playcardsdoppelkopfscore.usefulweb.app/): Doppelkopf game points from card points, announcements and special points (DDV rules). Part of [Playcards](https://playcards.usefulweb.app/) (ownerApp: playcards). API: POST https://playcards.usefulweb.app/api/v1/tools/playcards-doppelkopf-score/calculate · MCP tool `playcards_doppelkopf_score`
- [Blackjack Basic Strategy Calculator](https://playcardsblackjackstrategy.usefulweb.app/): Blackjack basic strategy chart and expected values computed for your table rules. Part of [Playcards](https://playcards.usefulweb.app/) (ownerApp: playcards). API: POST https://playcards.usefulweb.app/api/v1/tools/playcards-blackjack-strategy/calculate · MCP tool `playcards_blackjack_strategy`

## Formats
- Import: Playcards table (.playcards.json), Share link with the table set-up (#project=)
- Export: Playcards table (.playcards.json) with the running game, Share link with the table set-up (no cards), Score sheet as CSV

## Limits
- Online tables live in the server’s memory: a server restart ends running tables, and a table is removed after two hours without moves.
- Doppelkopf has no compulsory solo (Pflichtsolo), no Armut/poverty and no Schweinchen; the soloist does not lead the first trick (Lustsolo rule).
- Skat is played by three at one table; there is no four-player table with a sitting-out dealer, and Kontra/Re in Skat is not offered.
- Schlafmütze on one device needs every player to share the keyboard (each seat has its own grab key).
- Blackjack follows the US hole-card game with dealer peek; there is no European no-hole-card rule and no side bets.
- Computer players are strong amateurs, not tournament software; they do not use bidding conventions or Doppelkopf signalling systems.
- There is no chat; talk to your friends by your own means.