The game's whole vocabulary of threats is eight rules. The number is deliberately small: each rule has to be explainable in two sentences, readable on the board without text, and introducible on its own in a tutorial level.
The eight rules
| Rule | Taught in |
|---|---|
| NB-01 | 1-22-1 |
| NB-02 | 1-4 |
| NB-03 | 2-4 |
| NB-04 | 2-6 |
| NB-05 | 1-6 |
| NB-06 | 1-8 |
| NB-07 | 3-1 |
| NB-08 | 3-4 |
The tutorial levels in that table come from the level catalogue — there is not a single hand-written level number on this page. If the level that introduces a rule ever changes, this table corrects itself.
What each one does
- NB-01 · Sentry — Stands still, looks one way. Its sight is lethal. From act 2 there is a rotating variant.
- NB-02 · Patrol — Follows a closed route, advancing one edge per turn and facing the way it moves. Its sight is lethal.
- NB-03 · Chaser — Waits at its post; the moment it sees you it raises the alarm and comes for you by the shortest path. Its sight is not lethal; it catches only by contact.
- NB-04 · Bell stone — A tool on your side. Threats near the node you throw it at abandon their posts and walk towards the sound for three turns.
- NB-05 · Hiding spot — Another tool. While you stand on it you are invisible to the sight check, and enemies never step onto it.
- NB-06 · Door and key — Impassable until you hold the matching key; while shut it also blocks sight, and once opened it stays open for good.
- NB-07 · Toll — Entering a node costs coins. You pay on the first entry only, not on later ones.
- NB-08 · Caravan members — Some levels have more than one character, and each must reach their own exit. Switching between them does not cost a move.
How the catalogue grows
Adding a rule is not just writing a new behaviour: it needs an exact definition, a way for the player to read it on the board, a tutorial level that introduces it alone, and support in the solver. A rule whose definition cannot be given in two sentences does not get in.