About Open Mercy
Open Mercy is a free card game that runs in your browser. It is built and maintained by one developer, alii13, as an independent side project. There is no studio behind it and no publisher.
What the game is
Open Mercy plays by No Mercy-style rules on a 168-card deck: the usual numbers and actions, plus Draw 6, Draw 10, Skip Everyone, Discard All and Color Roulette. Draw cards stack, a 7 lets you swap hands, a 0 passes every hand around the table, and anyone who reaches 25 cards is out.
You can play two ways. Solo, you face one bot at a time on a ladder of eight, and beating one unlocks the next. Online, you open a room, send the code or link to friends, and play with up to 20 people. Every room picks one of three stacking modes before the deal. There is also a daily deal that gives everyone the same shuffle for the day.
You do not need an account to play. Pressing PLAY NOW gives you an anonymous guest seat. An account is optional and only keeps your stats.
How it is made
The game you see is a Vue app. Online games run on a realtime server on Cloudflare, where each room lives in its own small process, so a game keeps its state even if someone's connection drops for a moment. Accounts, profiles and game results are stored in Supabase.
The rules themselves are written once, in a shared rules engine that both the browser and the game server use. That is a deliberate choice: a solo game against a bot and an online game with friends follow the same code for what is legal, what stacks, and when someone is out. If a rule changes, it changes everywhere at once.
The source code is public on GitHub under the MIT license.
How rules are decided
The printed No Mercy rules are the baseline, and that is what the Official stacking mode plays. Where tables commonly play it differently, the game offers a mode for it instead of picking a side. House mode lets wild draw cards stack on anything. Casual mode lets any draw card answer any other.
The rules guide explains every card and edge case, and it is written against what the game actually does. If you find a place where the guide and the game disagree, that is a bug worth reporting.
How updates ship
Changes go out as small releases, often several in a month. Every player-facing change is listed on the changelog with its date. The bigger ones also show up once as a card inside the game, so regular players see them without having to look.
Getting in touch
Bug reports, rule questions and ideas are all welcome. The contact page explains where to send them and what details help most.