Visual Novel

A playbook for visual novels — the branching script, the presentation (text box, characters,
backgrounds), choices, and the quality-of-life systems players expect (save anywhere, backlog,
skip, auto). This is a compositional skill: it drives a dialogue engine and a UI layer. It
does not re-teach the dialogue engine or UI nodes; it defines the script model and the player
conveniences that make a VN pleasant to read.

When to use

• Use when the game is mostly reading branching text with character art and backgrounds:
  visual novel, dating sim, branching interactive fiction, story-choice game.
• Use when designing a choice/route structure, story flags, or VN conveniences (backlog,
  skip, auto-advance, save-anywhere).

When not to use: dialogue as one feature inside a larger game → rpg consuming
dialogue-systems. Card/board play → other genres. For the branching-script engine itself,
use dialogue-systems (Ink / Yarn Spinner).

Core loop

Read a line → advance → (at a branch) make a choice → the story branches on flags/choices →
read on → reach an ending. The "game" is the shape of the branching and whether choices
feel consequential; everything else is presentation and convenience.

Must-have systems

1. Branching script — ordered lines + choices + jumps, with conditions and variables (Ink/Yarn).
2. Text box — speaker name, body text, typewriter reveal, advance on click/key.
3. Characters — sprites with expressions/poses, positions, show/hide transitions.
4. Backgrounds + transitions — scene images, fades/dissolves.
5. Choices — present options, gate some on flags, record the pick.
6. Story state — flags/variables that branch the script and unlock content.
7. Save/load (save-anywhere) — full script position + state; multiple slots; quick save.
8. VN conveniences — backlog/history, skip (read text), auto-advance, text-speed setting.
9. Audio — music per scene, SFX, optional voice clips.

Design knobs

Patterns

1. Script as data the engine walks

# Pseudocode. Lines, choices, and jumps as data — usually authored in Ink/Yarn and stepped
# through by that runtime. The engine asks the script for "the next thing to show".
node = script.current()
if node.kind == "line":
    show_text(node.speaker, node.text)        # wait for advance input
elif node.kind == "choice":
    options = [o for o in node.options if condition_met(o.condition, flags)]  # gate by flags
    show_choices(options)                      # wait for selection
elif node.kind == "set":
    flags[node.var] = eval_expr(node.expr, flags)
script.advance(selected_option_or_none)

2. Typewriter reveal + advance (skippable)

# Pseudocode. Reveal characters over time; a click first completes the line, then advances.
def show_text(speaker, text):
    name_label.text = speaker
    revealed = 0
    while revealed < len(text):
        if advance_pressed():                  # first press: reveal the whole line instantly
            revealed = len(text); break
        revealed += chars_per_second * dt
        body_label.text = text[:int(revealed)]
        push_to_backlog_when_complete(speaker, text)
    wait_for_advance()                          # second press: go to the next line

3. Choice sets a flag that branches later content

# Pseudocode. Choices write flags; later conditions read them — that is "reactivity".
def on_choice(option):
    if option.set: flags[option.set] = True     # e.g. flags["helped_npc"] = True
    script.jump(option.target)                   # follow the branch

# Elsewhere, a line/choice/ending checks the flag:
if flags.get("helped_npc"): play_route("good_ending") else: play_route("neutral_ending")

Pitfalls / failure modes

• Save that only stores a checkpoint → VNs need save-anywhere. Persist the exact script
  position and all flags/variables (and seen-text data) so a load resumes the same line.
• Presentation logic baked into the script → unmaintainable. Keep content (text, choices)
  in the script and how it looks (sprites, transitions) in the engine layer.
• No skip/auto/backlog → readers feel trapped, especially on replays. These are expected
  baseline features, not extras.
• Skipping unread text → players miss content. Skip should fast-forward read text only.
• Choices with no consequence → branches that reconverge instantly feel fake. Set flags that
  visibly change later lines, choices, or endings.
• Combinatorial branch explosion → unshippable. Prefer branch-and-merge with a few flagged
  variations over fully distinct trees (refs).
• Lost reading context → no backlog to re-read the last lines. Keep a history buffer.
• Hardcoded language → no localization path. Keep text in data keyed for translation.

Composition (build it from these skills)

• Script engine: dialogue-systems (Ink / Yarn Spinner) — branching, conditions, variables, localization hooks.
• Presentation: game-ui-ux for text-box/choice-menu layout, scaling, and safe areas; godot-ui-control for the concrete text box, choice menu, name plate, and backlog UI.
• Persistence: save-systems for save-anywhere slots, seen-text/skip data, and settings.
• Audio: audio-design for per-scene music, SFX, and voice playback.
• Visuals: the engine animation/Tween skill for sprite/background transitions; shader-programming for dissolves.
• Process: prototype-fast to test the branch structure in plain text before adding art.

References

• For the branching data model, route structures (branch-and-merge vs. routes), flags/variables,
  save-anywhere + backlog/skip data, and the content/presentation split, read
  references/script-and-flow.md.