Yet Another Sim#

Yet Another Sim is a browser sandbox for practising FFXIV-style raid mechanics. It runs a deterministic simulation in every player's browser, relayed through a server so that up to eight people see exactly the same fight. Empty party slots are filled by bots, so you can drill a mechanic alone or with a full group.

Encounters are authored as YAML timelines, which means the simulator is also a tool for writing fights, not just playing them.

What is in the simulator today#

Encounters are grouped into categories in the raid browser, and the list comes from whatever raid files the server is serving — so what you see there depends on the deployment rather than being fixed by the client.

What every encounter is built from is the same:

• An eight-player roster of two tanks, two healers and four DPS, in fixed slots that mechanics target by name.
• An arena assembled from circles, rectangles and polygons, with waymarks. Anything outside the floor is a fall, and a fall is fatal.
• A timeline of mechanics resolving on a clock: area attacks of every shape, baited and targeted hits, tethers and chains, stacks and spreads, towers to soak, knockbacks, gazes, dashes and divebombs, limit cut ordering, and buffs and debuffs that change what a later mechanic does to you.
• Seeded per-pull variation, so a fight is not the same every time — and any of it can be pinned by the host to drill one case repeatedly.
• Bots filling every unclaimed slot, following movement authored alongside the encounter.
• A recording of each stopped pull, reviewable afterwards with every death and avoidable hit listed.

Alongside those there is a Debug category holding one small raid per mechanic type — towers, knockbacks, gazes, limit cut, and so on. Those are the fastest way to see a single mechanic in isolation, and they are what the authoring documentation uses for its examples.

What it does not simulate#

The simulator models positioning and mechanic resolution, not the rest of the game. There are no jobs, no rotations, no damage you deal, no aggro beyond a fixed tank assignment, and no healing you cast — recovery between mechanics is scripted into the timeline. Damage numbers exist only so that a mistake can kill you.