diff --git a/packages/ludic.needs/README.md b/packages/ludic.needs/README.md
new file mode 100644
index 00000000..df5aead8
--- /dev/null
+++ b/packages/ludic.needs/README.md
@@ -0,0 +1,55 @@
+# ludic.needs
+
+A body's four needs - warmth, food, water and energy, each a bar of 0..100 - what an hour of
+doing something costs them, and the countdown to a collapse when one runs out. Uses
+[`ludic.base`](../ludic.base/README.md) and nothing else.
+
+```ludic
+import "ludic.needs"
+```
+
+The package owns the rates (a full bar is a day at a real trip's median, about fourteen hours at
+the hardest sustained work, two days at rest) and the countdown. It never decides what a collapse
+COSTS: a need at zero is `NEEDS_CRITICAL`, ten seconds later it is `NEEDS_COLLAPSED`, and the game
+walks the player out, takes their money, or puts them down for a teammate. Say it happened with
+`needs_went_down()`, which counts it.
+
+## The port
+
+```ludic
+export port NeedsWorld {           # every member has a default, so any may be left out
+  activity: fn() -> int            # NEEDS_STILL, _WALK, _RUN, _SIT, _SWIM, _SWIM_HARD, _FLOAT, _DIVE
+  resting: fn() -> float           # energy an hour sitting gives back (unbound: 40)
+  warmth: fn() -> float            # warmth an hour from the surroundings: sun, night, weather, a fire, the water (unbound: -2)
+  keep: fn() -> float              # the fraction of warmth being lost that clothing keeps (unbound: 0)
+  hot: fn() -> bool                # the midday sun: thirst half again faster
+  effort: fn() -> float            # walking and running energy, times (the boots)
+  drain: fn(int) -> float          # a need's drain, times (difficulty, a survey's rule)
+  bonus: fn(int) -> float          # a need's gain an hour from outside (the effects)
+  thirst: fn() -> bool             # thirst is a need at all (unbound: yes); off, water holds full
+  gentle: fn() -> bool             # the needs stop at 22: no countdown, no collapse
+  held: fn() -> bool               # the body is already down: the countdown waits
+}
+```
+
+## API
+
+| | |
+| --- | --- |
+| `NEED_WARMTH`, `NEED_FOOD`, `NEED_WATER`, `NEED_ENERGY`, `NEED_COUNT` | the needs |
+| `needs_level(k)`, `needs_warmth()`, `needs_food()`, `needs_water()`, `needs_energy()`, `needs_lowest()` | the bars |
+| `needs_last_legs()`, `needs_last_need()`, `needs_collapses()` | the countdown's seconds (0: none), its need, and how many times the body went down |
+| `needs_pace()` | the walk's pace, times: full above fifty on each need, 0.6 at nothing, and 0.6 more on last legs |
+| `needs_can_run()` | energy over 8, and warmth, food and water over 20 |
+| `needs_feed(k, n)`, `needs_meal(food, water, energy)`, `needs_set(k, v)`, `needs_floor(k, v)` | the verbs; every bar is held to 0..100 |
+| `needs_after_night(rested, food_lost, water_lost)` | energy to `rested`, food never under 6, water never under 5 |
+| `needs_went_down()`, `needs_helped_up()`, `needs_calm()` | a collapse counted; a teammate's hand (nothing under 20); the countdown off, quietly |
+| `needs_run(gh)`, `needs_watch(dt)` | the drain over `gh` game hours, and the countdown over `dt` real seconds (the system's tick runs both) |
+| `needs_facts() -> Queue<NeedFact>` | `{ what, need }`: `NEEDS_CRITICAL`, `NEEDS_RESTORED`, `NEEDS_COLLAPSED` |
+| `needs_system() -> System` | `"needs"`, `PH_SIMULATE`: reset, tick, and its save section (`needs_save`, `needs_load`: the four bars and the collapses) |
+
+## Tests
+
+```bash
+ludic test packages/ludic.needs
+```
diff --git a/packages/ludic.needs/index.ludic b/packages/ludic.needs/index.ludic
new file mode 100644
index 00000000..f36e8859
--- /dev/null
+++ b/packages/ludic.needs/index.ludic
@@ -0,0 +1,12 @@
+# ludic.needs - four bars of 0..100 that the body's work drains and meals fill; one at zero starts
+# a countdown, and the countdown running out is a fact (a collapse) the game acts on
+module ludic_needs uses ludic_base
+numbers float
+import "ludic.base"
+import "state.ludic"
+import "rates.ludic"
+import "run.ludic"
+import "watch.ludic"
+import "queries.ludic"
+import "verbs.ludic"
+import "system.ludic"
diff --git a/packages/ludic.needs/package.ludic b/packages/ludic.needs/package.ludic
new file mode 100644
index 00000000..a8b3c3cb
--- /dev/null
+++ b/packages/ludic.needs/package.ludic
@@ -0,0 +1,5 @@
+# ludic.needs - a body's four needs (warmth, food, water, energy), what an hour of doing something
+# costs them, and the countdown to a collapse when one runs out. Uses ludic.base and nothing else.
+package "ludic.needs"
+version "0.1.0"
+kind source
diff --git a/packages/ludic.needs/queries.ludic b/packages/ludic.needs/queries.ludic
new file mode 100644
index 00000000..25761ccc
--- /dev/null
+++ b/packages/ludic.needs/queries.ludic
@@ -0,0 +1,36 @@
+# queries.ludic - what the world asks the body
+export function needs_level(k: int) -> float {
+  if not nd_ok(k) { return 0.0 }
+  return nd_lv()[k]
+}
+
+export function needs_warmth() -> float { return nd_lv()[NEED_WARMTH] }
+export function needs_food() -> float { return nd_lv()[NEED_FOOD] }
+export function needs_water() -> float { return nd_lv()[NEED_WATER] }
+export function needs_energy() -> float { return nd_lv()[NEED_ENERGY] }
+
+# seconds left before a collapse (0: no countdown), and the need it is for
+export function needs_last_legs() -> float { return nd_legs }
+export function needs_last_need() -> int { return nd_last }
+export function needs_collapses() -> int { return nd_collapses }
+
+# the walk's pace, times: the ramp of each need, and 0.6 more on last legs
+export function needs_pace() -> float {
+  let lv = nd_lv()
+  var m = nd_pace(lv[NEED_WARMTH]) * nd_pace(lv[NEED_FOOD])
+  if NeedsWorld.thirst() { m = m * nd_pace(lv[NEED_WATER]) }
+  if nd_legs > 0.0 { m = m * 0.6 }
+  return m
+}
+
+# running needs legs, calories and a body that is not already in trouble
+export function needs_can_run() -> bool {
+  let lv = nd_lv()
+  return lv[NEED_ENERGY] > 8.0 and lv[NEED_FOOD] > 20.0 and lv[NEED_WARMTH] > 20.0 and lv[NEED_WATER] > 20.0
+}
+
+# the lowest of the four
+export function needs_lowest() -> float {
+  let lv = nd_lv()
+  return Math.min(Math.min(lv[NEED_WARMTH], lv[NEED_FOOD]), Math.min(lv[NEED_WATER], lv[NEED_ENERGY]))
+}
diff --git a/packages/ludic.needs/rates.ludic b/packages/ludic.needs/rates.ludic
new file mode 100644
index 00000000..063c8d8e
--- /dev/null
+++ b/packages/ludic.needs/rates.ludic
@@ -0,0 +1,65 @@
+# rates.ludic - what an hour costs, by what the body is doing. A full bar is a DAY at the median
+# of a real trip (walking, some standing, an hour by the fire): 100 / 24 is about 4.2 an hour.
+# The hardest sustained work (running, the midday sun, the lake) empties it in about fourteen,
+# so the caps are the product of the multipliers, never each of them; at rest it lasts two days.
+const NEED_FOOD_CAP: float = 7.2
+const NEED_WATER_CAP: float = 7.5
+
+function nd_hard(a: int) -> bool { return a == NEEDS_RUN or a == NEEDS_SWIM_HARD }
+function nd_swim(a: int) -> bool { return a >= NEEDS_SWIM }
+
+function nd_food_rate(a: int) -> float {
+  var eat = 4.0
+  if nd_hard(a) { eat = 6.8 }
+  if a == NEEDS_SIT { eat = eat * 0.75 }
+  return Math.min(eat, NEED_FOOD_CAP)
+}
+
+# thirst follows the work rather than the clock: a run, the sun and the lake (you sweat
+# swimming and never notice) all pull it down, up to the day's cap
+function nd_water_rate(a: int) -> float {
+  var drink = 3.8
+  if a == NEEDS_WALK or a == NEEDS_SWIM or a == NEEDS_DIVE { drink = 4.6 }
+  if nd_hard(a) { drink = 7.0 }
+  if nd_swim(a) { drink = drink * 1.6 }
+  if NeedsWorld.hot() { drink = drink * 1.5 }
+  if a == NEEDS_SIT { drink = drink * 0.6 }
+  return Math.min(drink, NEED_WATER_CAP)
+}
+
+# the water costs more than running, and the cold is the real limit rather than the legs
+function nd_energy_rate(a: int) -> float {
+  if a == NEEDS_SIT { return NeedsWorld.resting() }
+  if a == NEEDS_WALK { return -5.0 * NeedsWorld.effort() }
+  if a == NEEDS_RUN { return -22.0 * NeedsWorld.effort() }
+  if a == NEEDS_SWIM { return -28.0 }
+  if a == NEEDS_SWIM_HARD { return -38.0 }
+  if a == NEEDS_FLOAT { return -6.0 }
+  if a == NEEDS_DIVE { return -34.0 }
+  return -2.0
+}
+
+# the surroundings, then the lake taking it, the effort giving a little back, clothing keeping
+# some of what is lost, and a dry body holding heat badly
+function nd_warmth_rate(a: int, water: float) -> float {
+  var wr = NeedsWorld.warmth()
+  if nd_swim(a) {
+    wr = Math.min(wr, 0.0) - 24.0
+    if a == NEEDS_SWIM_HARD { wr = wr + 2.0 }
+    if a == NEEDS_FLOAT { wr = wr - 2.0 }
+    if a == NEEDS_DIVE { wr = wr - 6.0 }
+  }
+  if nd_hard(a) { wr = wr + 3.0 }
+  let keep = Math.clamp(NeedsWorld.keep(), 0.0, 1.0)
+  if keep > 0.0 and wr < 0.0 { wr = wr * (1.0 - keep) }
+  if water < 25.0 and wr < 0.0 { wr = wr * 1.25 }
+  return wr + NeedsWorld.bonus(NEED_WARMTH)
+}
+
+# under fifty a need is felt in the legs before it is a crisis: full pace above fifty, three
+# quarters at twenty, 0.6 at nothing - one continuous line, steeper below twenty
+function nd_pace(v: float) -> float {
+  if not (v < 50.0) { return 1.0 }
+  if v < 20.0 { return 0.75 - 0.15 * ((20.0 - v) / 20.0) }
+  return 1.0 - 0.25 * ((50.0 - v) / 30.0)
+}
diff --git a/packages/ludic.needs/run.ludic b/packages/ludic.needs/run.ludic
new file mode 100644
index 00000000..5585eff6
--- /dev/null
+++ b/packages/ludic.needs/run.ludic
@@ -0,0 +1,15 @@
+# run.ludic - `gh` game hours of whatever the body is doing, taken out of the four bars
+function nd_add(k: int, d: float) -> void {
+  let lv = nd_lv()
+  lv[k] = Math.clamp(lv[k] + d, 0.0, 100.0)
+}
+
+export function needs_run(gh: float) -> void {
+  let a = NeedsWorld.activity()
+  nd_add(NEED_FOOD, (NeedsWorld.bonus(NEED_FOOD) - nd_food_rate(a) * NeedsWorld.drain(NEED_FOOD)) * gh)
+  if NeedsWorld.thirst() {
+    nd_add(NEED_WATER, (NeedsWorld.bonus(NEED_WATER) - nd_water_rate(a) * NeedsWorld.drain(NEED_WATER)) * gh)
+  } else { nd_lv()[NEED_WATER] = 100.0 }
+  nd_add(NEED_ENERGY, (nd_energy_rate(a) + NeedsWorld.bonus(NEED_ENERGY)) * gh)
+  nd_add(NEED_WARMTH, nd_warmth_rate(a, nd_lv()[NEED_WATER]) * gh)
+}
diff --git a/packages/ludic.needs/state.ludic b/packages/ludic.needs/state.ludic
new file mode 100644
index 00000000..33d88d6c
--- /dev/null
+++ b/packages/ludic.needs/state.ludic
@@ -0,0 +1,88 @@
+# state.ludic - the needs, what the body is doing, the port, the facts, and what the body holds
+export const NEED_WARMTH: int = 0
+export const NEED_FOOD: int = 1
+export const NEED_WATER: int = 2
+export const NEED_ENERGY: int = 3
+export const NEED_COUNT: int = 4
+
+# what the body is doing, which is what an hour costs
+export const NEEDS_STILL: int = 0
+export const NEEDS_WALK: int = 1
+export const NEEDS_RUN: int = 2
+export const NEEDS_SIT: int = 3
+export const NEEDS_SWIM: int = 4
+export const NEEDS_SWIM_HARD: int = 5
+export const NEEDS_FLOAT: int = 6
+export const NEEDS_DIVE: int = 7
+
+# what the needs ask the world. Every member has a default: standing still in mild air, no
+# clothing, no multipliers, no bonuses, thirst on, a collapse possible, the body up.
+export port NeedsWorld {
+  activity: fn() -> int = fn nd_still           # NEEDS_* above
+  resting: fn() -> float = fn nd_rest            # energy an hour sitting gives back (the seat's say)
+  warmth: fn() -> float = fn nd_mild             # warmth an hour from the surroundings: sun, night, weather, a fire, the water
+  keep: fn() -> float = fn nd_none               # the fraction of warmth being lost that clothing keeps
+  hot: fn() -> bool = fn nd_no                   # the midday sun: thirst runs half again faster
+  effort: fn() -> float = fn nd_one              # what moving costs in energy, times (the boots)
+  drain: fn(int) -> float = fn nd_one_of         # a need's drain, times (the difficulty, a survey's rule)
+  bonus: fn(int) -> float = fn nd_none_of        # a need's gain an hour from outside (a meal's warmth, a drink's legs)
+  thirst: fn() -> bool = fn nd_yes               # thirst is a need at all; off, water holds full
+  gentle: fn() -> bool = fn nd_no                # the needs stop above trouble: no countdown, no collapse
+  held: fn() -> bool = fn nd_no                  # the body is already down: the countdown waits
+}
+function nd_still() -> int { return NEEDS_STILL }
+function nd_rest() -> float { return 40.0 }
+function nd_mild() -> float { return -2.0 }
+function nd_none() -> float { return 0.0 }
+function nd_no() -> bool { return false }
+function nd_yes() -> bool { return true }
+function nd_one() -> float { return 1.0 }
+function nd_one_of(k: int) -> float { return 1.0 }
+function nd_none_of(k: int) -> float { return 0.0 }
+
+# what happened: a need ran out and the countdown began, every need came back above the line, or
+# the countdown ran out - the game decides what a collapse costs and says so
+export const NEEDS_CRITICAL: int = 0
+export const NEEDS_RESTORED: int = 1
+export const NEEDS_COLLAPSED: int = 2
+
+export property NeedFact {
+  what: int = 0
+  need: int = 0
+}
+
+var nd_level: []float = null
+var nd_legs: float = 0.0          # seconds left before a collapse, 0 = none
+var nd_last: int = 0              # the need the countdown is for
+var nd_collapses: int = 0
+var nd_facts: Queue<NeedFact> = null
+
+function nd_lv() -> []float {
+  if nd_level == null {
+    nd_level = floats(NEED_COUNT)
+    nd_fill()
+  }
+  return nd_level
+}
+
+function nd_fill() -> void {
+  nd_level[NEED_WARMTH] = 100.0
+  nd_level[NEED_FOOD] = 70.0
+  nd_level[NEED_WATER] = 85.0
+  nd_level[NEED_ENERGY] = 100.0
+}
+
+# the facts, oldest first; the game drains them into its notices and its collapse
+export function needs_facts() -> Queue<NeedFact> {
+  if nd_facts == null { nd_facts = queue_new("needs.facts") }
+  return nd_facts
+}
+
+function nd_fact(what: int, need: int) -> void {
+  let f = new NeedFact
+  f.what = what
+  f.need = need
+  q_push(needs_facts(), f)
+}
+
+function nd_ok(k: int) -> bool { return k >= 0 and k < NEED_COUNT }
diff --git a/packages/ludic.needs/system.ludic b/packages/ludic.needs/system.ludic
new file mode 100644
index 00000000..365282d1
--- /dev/null
+++ b/packages/ludic.needs/system.ludic
@@ -0,0 +1,34 @@
+# system.ludic - the needs as a system: PH_SIMULATE, the drain then the watch, and its own save
+# section (the countdown is not saved: a loaded body starts it again if a need is still empty)
+function needs_tick(t: Tick) -> void {
+  needs_run(t.hours)
+  needs_watch(t.dt)
+}
+
+export function needs_save() -> Val {
+  let v = Value.object()
+  sv_put_float(v, "warmth", needs_warmth())
+  sv_put_float(v, "food", needs_food())
+  sv_put_float(v, "water", needs_water())
+  sv_put_float(v, "energy", needs_energy())
+  sv_put_int(v, "collapses", nd_collapses)
+  return v
+}
+
+export function needs_load(v: Val, version: int) -> void {
+  needs_reset()
+  needs_set(NEED_WARMTH, sv_float(v, "warmth", 100.0))
+  needs_set(NEED_FOOD, sv_float(v, "food", 70.0))
+  needs_set(NEED_WATER, sv_float(v, "water", 85.0))
+  needs_set(NEED_ENERGY, sv_float(v, "energy", 100.0))
+  nd_collapses = sv_int(v, "collapses", 0)
+}
+
+export function needs_system() -> System {
+  let s = system_new("needs", PH_SIMULATE)
+  s.reset = fn needs_reset
+  s.tick = fn needs_tick
+  s.save = fn needs_save
+  s.load = fn needs_load
+  return s
+}
diff --git a/packages/ludic.needs/tests/needs_test.ludic b/packages/ludic.needs/tests/needs_test.ludic
new file mode 100644
index 00000000..334728b2
--- /dev/null
+++ b/packages/ludic.needs/tests/needs_test.ludic
@@ -0,0 +1,210 @@
+# needs_test.ludic - a full bar is a day, work drains faster, the port's multipliers and bonuses
+# count, meals fill, a need at zero counts down to a collapse as a fact, and the save reads back
+import "ludic.needs"
+import "ludic.base"
+program NeedsTest {
+  numbers float
+  var act: int = 0
+  var air: float = -2.0
+  var keep: float = 0.0
+  var hot: bool = false
+  var thirst: bool = true
+  var gentle: bool = false
+  var held: bool = false
+  var food_mult: float = 1.0
+  var warm_bonus: float = 0.0
+
+  function fake_act() -> int { return act }
+  function fake_air() -> float { return air }
+  function fake_keep() -> float { return keep }
+  function fake_hot() -> bool { return hot }
+  function fake_thirst() -> bool { return thirst }
+  function fake_gentle() -> bool { return gentle }
+  function fake_held() -> bool { return held }
+  function fake_drain(k: int) -> float {
+    if k == NEED_FOOD { return food_mult }
+    return 1.0
+  }
+  function fake_bonus(k: int) -> float {
+    if k == NEED_WARMTH { return warm_bonus }
+    return 0.0
+  }
+
+  bind NeedsWorld {
+    activity: fn fake_act
+    warmth: fn fake_air
+    keep: fn fake_keep
+    hot: fn fake_hot
+    thirst: fn fake_thirst
+    gentle: fn fake_gentle
+    held: fn fake_held
+    drain: fn fake_drain
+    bonus: fn fake_bonus
+  }
+
+  function fresh() -> void { needs_reset() }
+  function hours(h: float) -> void { for i in 0 .. int(h * 10.0) { needs_run(0.1) } }
+  function facts() -> []NeedFact { return q_drain(needs_facts()) }
+
+  test "a new body is warm, rested, fed and watered" {
+    fresh()
+    expect(needs_warmth() == 100.0)
+    expect(needs_energy() == 100.0)
+    expect(needs_food() == 70.0)
+    expect(needs_water() == 85.0)
+    expect(needs_pace() == 1.0)
+    expect(needs_can_run())
+  }
+
+  test "a walking day empties a full bar of food in about a day, a run much sooner" {
+    fresh()
+    needs_set(NEED_FOOD, 100.0)
+    act = NEEDS_WALK
+    hours(12.0)
+    expect_near(needs_food(), 52.0, 0.5)
+    needs_set(NEED_FOOD, 100.0)
+    act = NEEDS_RUN
+    hours(12.0)
+    expect(needs_food() < 20.0)
+  }
+
+  test "the sun and the lake make thirst faster, but never past the cap" {
+    fresh()
+    needs_set(NEED_WATER, 100.0)
+    act = NEEDS_SWIM_HARD
+    hot = true
+    hours(1.0)
+    expect_near(needs_water(), 92.5, 0.01)
+  }
+
+  test "thirst off holds water full" {
+    fresh()
+    thirst = false
+    needs_set(NEED_WATER, 10.0)
+    hours(1.0)
+    expect(needs_water() == 100.0)
+  }
+
+  test "the port's drain and bonus are what the bars get" {
+    fresh()
+    food_mult = 2.0
+    hours(1.0)
+    expect_near(needs_food(), 62.0, 0.01)
+    warm_bonus = 10.0
+    air = 0.0
+    needs_set(NEED_WARMTH, 50.0)
+    hours(1.0)
+    expect_near(needs_warmth(), 60.0, 0.01)
+  }
+
+  test "clothing keeps what is being lost, and a dry body loses more" {
+    fresh()
+    air = -20.0
+    keep = 0.5
+    hours(1.0)
+    expect_near(needs_warmth(), 90.0, 0.01)
+    needs_set(NEED_WARMTH, 100.0)
+    needs_set(NEED_WATER, 10.0)
+    keep = 0.0
+    hours(1.0)
+    expect_near(needs_warmth(), 75.0, 0.01)
+  }
+
+  test "sitting gives energy back, swimming takes it" {
+    fresh()
+    needs_set(NEED_ENERGY, 40.0)
+    act = NEEDS_SIT
+    hours(1.0)
+    expect_near(needs_energy(), 80.0, 0.01)
+    act = NEEDS_SWIM
+    hours(1.0)
+    expect_near(needs_energy(), 52.0, 0.01)
+  }
+
+  test "meals fill, and every bar is held to 0..100" {
+    fresh()
+    needs_meal(50.0, 50.0, 10.0)
+    expect(needs_food() == 100.0)
+    expect(needs_water() == 100.0)
+    needs_feed(NEED_ENERGY, -150.0)
+    expect(needs_energy() == 0.0)
+    needs_floor(NEED_ENERGY, 30.0)
+    expect(needs_energy() == 30.0)
+  }
+
+  test "a need at zero is a countdown, then a collapse, as facts" {
+    fresh()
+    needs_set(NEED_WATER, 0.0)
+    needs_watch(0.1)
+    let a = facts()
+    expect_eq(len(a), 1)
+    expect_eq(a[0].what, NEEDS_CRITICAL)
+    expect_eq(a[0].need, NEED_WATER)
+    expect(needs_last_legs() > 0.0)
+    expect(needs_pace() < 0.6)
+    var i = 0
+    while q_len(needs_facts()) == 0 and i < 200 {
+      needs_watch(0.1)
+      i += 1
+    }
+    let b = facts()
+    expect_eq(len(b), 1)
+    expect_eq(b[0].what, NEEDS_COLLAPSED)
+    expect_eq(b[0].need, NEED_WATER)
+    expect(i >= 99 and i <= 101)
+    expect_eq(needs_collapses(), 0)
+    needs_went_down()
+    expect_eq(needs_collapses(), 1)
+  }
+
+  test "a drink in time calls the countdown off" {
+    fresh()
+    needs_set(NEED_FOOD, 0.0)
+    needs_watch(0.1)
+    needs_feed(NEED_FOOD, 30.0)
+    needs_watch(0.1)
+    let f = facts()
+    expect_eq(len(f), 2)
+    expect_eq(f[1].what, NEEDS_RESTORED)
+    expect(needs_last_legs() == 0.0)
+  }
+
+  test "gentle never counts down, and a body already down waits" {
+    fresh()
+    gentle = true
+    needs_set(NEED_WARMTH, 0.0)
+    needs_watch(0.1)
+    expect(needs_warmth() == 22.0)
+    expect_eq(q_len(needs_facts()), 0)
+    gentle = false
+    held = true
+    needs_set(NEED_WARMTH, 0.0)
+    needs_watch(0.1)
+    expect_eq(q_len(needs_facts()), 0)
+  }
+
+  test "a hand up costs the body but leaves nothing below twenty" {
+    fresh()
+    needs_set(NEED_FOOD, 25.0)
+    needs_helped_up()
+    expect(needs_food() == 20.0)
+    expect(needs_warmth() == 85.0)
+    expect(needs_energy() == 75.0)
+  }
+
+  test "a save section reads back the same body" {
+    fresh()
+    needs_set(NEED_FOOD, 33.5)
+    needs_set(NEED_WARMTH, 12.25)
+    needs_went_down()
+    let root = save_tree()
+    save_section(root, "needs", 1, needs_save())
+    let text = save_encode(root)
+    needs_reset()
+    let n = load_section(save_decode(text), "needs")
+    needs_load(n.data, n.version)
+    expect(needs_food() == 33.5)
+    expect(needs_warmth() == 12.25)
+    expect_eq(needs_collapses(), 1)
+  }
+}
diff --git a/packages/ludic.needs/verbs.ludic b/packages/ludic.needs/verbs.ludic
new file mode 100644
index 00000000..d0632389
--- /dev/null
+++ b/packages/ludic.needs/verbs.ludic
@@ -0,0 +1,58 @@
+# verbs.ludic - the only way the needs change from outside; each is held to 0..100
+# `n` more of a need (less, when negative): a meal, a drink, a shove from a bear
+export function needs_feed(k: int, n: float) -> void {
+  if nd_ok(k) { nd_add(k, n) }
+}
+
+# a meal: food, water and energy at once
+export function needs_meal(food: float, water: float, energy: float) -> void {
+  nd_add(NEED_FOOD, food)
+  nd_add(NEED_WATER, water)
+  nd_add(NEED_ENERGY, energy)
+}
+
+export function needs_set(k: int, v: float) -> void {
+  if nd_ok(k) { nd_lv()[k] = Math.clamp(v, 0.0, 100.0) }
+}
+
+# at least `v`
+export function needs_floor(k: int, v: float) -> void {
+  if nd_ok(k) and nd_lv()[k] < v { needs_set(k, v) }
+}
+
+# a night: rested to what it was worth, hungrier and thirstier for it, but never empty
+export function needs_after_night(rested: float, food_lost: float, water_lost: float) -> void {
+  let lv = nd_lv()
+  lv[NEED_ENERGY] = Math.clamp(rested, 0.0, 100.0)
+  lv[NEED_FOOD] = Math.max(lv[NEED_FOOD] - food_lost, 6.0)
+  if water_lost > 0.0 { lv[NEED_WATER] = Math.max(lv[NEED_WATER] - water_lost, 5.0) }
+}
+
+# the countdown called off, and nothing said (a wake, a load, a test)
+export function needs_calm() -> void { nd_legs = 0.0 }
+
+# the body went down, however: one more collapse, and no countdown running
+export function needs_went_down() -> void {
+  nd_collapses += 1
+  nd_legs = 0.0
+}
+
+# a hand up: the cost is in the body, and nothing goes below twenty
+export function needs_helped_up() -> void {
+  let lv = nd_lv()
+  lv[NEED_WARMTH] = Math.max(20.0, lv[NEED_WARMTH] - 15.0)
+  lv[NEED_FOOD] = Math.max(20.0, lv[NEED_FOOD] - 15.0)
+  lv[NEED_WATER] = Math.max(20.0, lv[NEED_WATER] - 15.0)
+  lv[NEED_ENERGY] = Math.max(20.0, lv[NEED_ENERGY] - 25.0)
+  nd_legs = 0.0
+}
+
+# a new trip: fed, watered, rested and warm, and never walked out
+export function needs_reset() -> void {
+  nd_lv()
+  nd_fill()
+  nd_legs = 0.0
+  nd_last = 0
+  nd_collapses = 0
+  q_clear(needs_facts())
+}
diff --git a/packages/ludic.needs/watch.ludic b/packages/ludic.needs/watch.ludic
new file mode 100644
index 00000000..22f86f57
--- /dev/null
+++ b/packages/ludic.needs/watch.ludic
@@ -0,0 +1,53 @@
+# watch.ludic - last legs: warmth, food or water at zero starts ten seconds of countdown; anything
+# above five on all three calls it off; the countdown running out is a collapse, as a fact
+const LAST_LEGS: float = 10.0
+const GENTLE_FLOOR: float = 22.0
+
+function nd_empty() -> int {
+  let lv = nd_lv()
+  if lv[NEED_WARMTH] == 0.0 { return NEED_WARMTH }
+  if lv[NEED_FOOD] == 0.0 { return NEED_FOOD }
+  if lv[NEED_WATER] == 0.0 { return NEED_WATER }
+  return -1
+}
+
+function nd_clear() -> bool {
+  let lv = nd_lv()
+  return lv[NEED_WARMTH] > 5.0 and lv[NEED_FOOD] > 5.0 and lv[NEED_WATER] > 5.0
+}
+
+# Gentle: a need that runs down stops just above where the legs start to go
+function nd_gentle() -> void {
+  let lv = nd_lv()
+  lv[NEED_WARMTH] = Math.max(lv[NEED_WARMTH], GENTLE_FLOOR)
+  lv[NEED_FOOD] = Math.max(lv[NEED_FOOD], GENTLE_FLOOR)
+  lv[NEED_WATER] = Math.max(lv[NEED_WATER], GENTLE_FLOOR)
+  nd_legs = 0.0
+}
+
+# `dt` real seconds; run it after everything this frame that could fill a need
+export function needs_watch(dt: float) -> void {
+  if NeedsWorld.held() { return }
+  if NeedsWorld.gentle() {
+    nd_gentle()
+    return
+  }
+  let need = nd_empty()
+  if need < 0 {
+    if nd_legs > 0.0 and nd_clear() {
+      nd_legs = 0.0
+      nd_fact(NEEDS_RESTORED, nd_last)
+    }
+    return
+  }
+  if nd_legs == 0.0 {
+    nd_legs = LAST_LEGS
+    nd_last = need
+    nd_fact(NEEDS_CRITICAL, need)
+    return
+  }
+  nd_legs = nd_legs - dt
+  if nd_legs > 0.0 { return }
+  nd_legs = 0.0
+  nd_fact(NEEDS_COLLAPSED, nd_last)
+}