How Prisma Duel works

Prisma Duel is a free, top-down, turn-based space combat game that runs in a browser tab. You fly one fighter in a mirrored arena strewn with dichroic crystals. Nothing happens in real time: each turn you set a course, decide whether to fire, and commit — then every pilot's orders resolve together over about four seconds, and you watch what your guesses actually did.

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The turn

Everybody plans at the same time, against a clock. When the last pilot commits — or the clock runs out, in which case your fighter simply holds its last course — the turn executes for everyone at once. There is no initiative order and no waiting your turn. This is the we-go or simultaneous turn structure that games like Frozen Synapse and Combat Mission use, and that Critical Mass used before them: the tension is that you are aiming at where someone will be in four seconds, not at where they are now.

One control, and it is out on the arena

Drag the handle at the end of your course line. The direction you drag is your heading; how far you drag is your speed. The arrow keys do the same job if you prefer them, with Shift for a finer step when you are threading a shot through a crystal.

Speed is bought from the same power the laser capacitor wants. A long drag is a fast run with nothing left to charge with; a short one is a tight turn that fills the capacitor. The orders panel shows you the split, but nothing in that panel is settable — the drag is the whole interface. Your course carries over between turns, so holding a curve is what happens if you do nothing.

The laser

The beam is welded to your nose. There is no turret, no lead indicator and no lock. Damage is charged per millisecond of dwell: a graze costs a few points, and holding somebody in the beam for a whole turn is fatal. Because hitting anything means turning to track it, and turning is exactly what your throttle just made expensive, every shot is an argument with your own speed.

Firing spends the entire capacitor and suppresses shield regeneration for that turn. Shields absorb before hull, and they only come back on turns you keep the laser cold.

The beam is not a line with a hit test on it. It is a real spectral ray tracer — ninety-odd wavelengths, Snell, Fresnel and dispersion — and the damage is the light that actually lands. How the laser works goes through it with live examples.

Crystals, mirrors and the closing walls

Every crystal is cut differently — five to eight faces, each vertex at its own radius and angle, generated from the arena seed — so no two arenas look alike. They are solid cover, and they refract. Fire through one and your beam bends, disperses into a rainbow fan, and can strike pilots who were never in your line of sight. The arena walls are mirrors, so a bank shot is a real tactic, including the bank shot that comes back and hits you. Flying into either is fatal.

From turn seven the box tightens. Once it is as small as it goes it begins to collapse, hurting everyone still alive by an escalating amount, so two careful pilots cannot circle each other forever — measured with no shots fired at all, every match still ends by turn 36.

Playing it

Practice puts you against three bots and needs no server at all. Multiplayer takes up to four pilots: enter a room code, or leave it blank to be matched. Any pair of players that can reach each other plays peer-to-peer, and any pair that cannot falls back to a relay, so a match survives most networks. How multiplayer works has the details.

Drag / Arrows

set your course — Shift for a fine step

F

arm the laser

Enter

commit your orders

0

reset the view

H

hide the interface

?

the manual, in the game

Where it comes from

Prisma Duel is an homage to Critical Mass, Sean O'Connor's turn-based squadron game for Windows from 1996. The overhead view, the secret orders, the simultaneous resolution you sit and watch, and above all the control — a course you drag out in front of the ship, with momentum you have to plan around — are his. The story of Critical Mass, and other games like it, are on their own pages.