Prismwar is a six-color trading card game that plays against a computer rival entirely inside your browser, with no account and no network requests. It is free on the Chrome Web Store as of today.
Here is forty seconds of it running, before any of the explanation.
What is the sixth color for?
Five of the colors will look familiar to anyone who has played a color-pie card game. Order goes wide and holds a line. Current draws and slips past blockers. Ledger trades everything and gets paid for it. Spark wants the game over before turn eight. Root ramps and grows the biggest bodies in the set.
The sixth is the reason the game exists. Undertow, the purple, does not destroy your opponent’s units. It takes them, and it keeps them. Every other color answers a threat by removing it; Undertow answers it by owning it, which means the board you are looking at can become the board you are playing against. Glimpse their hand, Ensnare the thing you want, and it is yours for the rest of the match.
That single rule is what stops this being a reskin. A color whose identity is acquisition changes how every other color evaluates its own board, because now a creature you commit is a creature you might be lending.
There is no server, and there is no store
Prismwar makes no network requests of its own. The extension declares connect-src 'none' in its content security policy, so Chrome blocks them at the browser level rather than asking you to take my word for it. It requests exactly one permission, storage.
There is nothing to buy. Packs come from playing: three daily quests, fifteen achievements, a pack for the first win of the day, and dust for every match and every three-win streak. Slot four of a pack is always Uncommon or better, slot five always Rare or better, and the odds are printed inside the game rather than in a legal footer.
The ten Ascendants never appear in packs at all. They unlock with codes I issue, each signed with ECDSA P-256 and checked on your device against a public key built into the game. No server is asked whether a code is real, which is the only way that check could work in something that cannot make a request.
A rival that can explain itself
The computer player scores every legal play, trade, block and ambush one move ahead and takes the best line. That is not novel. What I added in 0.6.0 is that the match summary now lists the turns that decided the game and why it chose what it chose.
That came out of watching people lose and not know why. An opponent that beats you silently teaches you nothing, and a card game you cannot learn from is a card game you play twice.
The first twenty minutes got all the work
Version 0.6.0 is almost entirely about where a new player stalls. Press a color and Quick build assembles a legal forty-card deck from the cards you actually own, cheap spells first, with the Wellsprings split evenly — and it refuses rather than padding a thin collection out to forty. The deck editor says in plain words when your color pips have no Wellspring that can pay them, and none of that advice blocks Save.
Every card now carries its color letter and a colored edge stripe, so the six colors stay separable without relying on hue. That one started as an accessibility fix and turned out to make the board faster to read for everyone.
Two builds, and they are not the same build
The Chrome extension is 0.6.0 and is the one that gets new work. The browser version at the DHSeaDev Arcade is the earlier 0.3.1 alpha, free to play with no install and no account, and it is staying where it is for now. Saves are not shared between them, which is a consequence of neither of them having a server rather than a decision.
Both print a ledger card: collection count, packs opened, record, achievements, deck list, and a Sig line that fingerprints those numbers so an edited save says so on its own card. Posting it to the shared Ledger Wall is optional and always a deliberate click.
Where to get it
Install it from the Chrome Web Store, or play the alpha in a tab at the Arcade. The project page has the full breakdown, the privacy policy and the change history; the build notes are in a round trip cannot test its own driver, which is about the replay format and the defect forty-five green assertions could not see. Everything else I have shipped is on the games index and the projects page.