What This System Is Doing
This is Lancer's ruleset, rebuilt so that a Game Master who is an AI can run it without the state quietly falling apart. Before you extend it, understand what was changed and why, because most of the conventions in this manual follow from one decision.
The decision
Lancer's mech combat is a grid wargame. It needs exact positions held across dozens of turns, line-of-sight traced between two points, cover resolved by adjacency, flanking resolved by geometry, and area templates measured in spaces.
A narrating AI cannot hold that. Not because the rules are complex — because the state is spatial and there is no board to hold it on. Craft's maps are authored assets; nothing moves tokens during play.
So the grid was replaced with zones, and every distance in the compendium was converted once, at authoring time. That is the load-bearing rule of this whole system:
Nothing in this game converts a distance at the table.
If you add content that says "5 spaces", you have broken it. The conversion table is in the Converting from the Grid rules chapter. Use it, once, while you write the entry.
What was preserved
Everything else, essentially. The dice, accuracy and difficulty, GRIT, the pilot, backgrounds, triggers, mech skills, talents, licences, core bonuses, the LL0–12 progression, all mech arithmetic, heat, structure, stress, both damage tables, every status and condition, the mission cycle, downtime, and the whole of narrative play.
Where you see a difference from the tabletop game, it is either a zone conversion or it is a bug. Report it as a bug.
What was traded away
Traced line of sight. Flanking geometry. Cover adjacency. Flight ceilings. Falling distance. Size-summing in multi-party grapples. Ship, squad and space-combat scale, which are deferred rather than cut.
Reactions became declared stances, because a reaction that interrupts mid-movement cannot be narrated reliably — the GM would have to stop its own sentence, and it will not.
The three invariants
Any content you add must hold these:
- Range is a band, never a number. ENGAGED, NEAR, FAR.
- Area is a target count, never a radius. single, pair, zone, engaged-burst, self-zone.
- Anything that changes during play is a stored field with a rule that orders the write.
The third one is the one people break.