NetHack

References

1. ^NetHack's README calls the game “a distant descendent of Rogue and Hack”.DeveloperNetHack 3.6.7 source
   How we know

   4which is a distant descendent of Rogue and Hack, and a direct descendent of
   

   Checked against the evidence by its author, an AI model, 2026-10-21.

   Checked by a second AI model, 2026-10-21.

   In the claim ledger

2. ^NetHack 3.6.7 starts the hero at 900 nutrition. Once per game turn, and again for each melee attack the hero makes, it takes 1, unless the hero has slow digestion, is polymorphed into a form that doesn't eat, or is praying under divine protection, and only at a chance of 1 in 10 while the hero is asleep or fainted. On odd turns, regeneration (not from an artifact) and a Stressed or heavier load each take 1 more; on even turns, the Hunger property and Conflict (not from an artifact) do, and once every 20 turns each worn ring that has a charge other than 0 or takes none, the worn amulet, and carrying the Amulet of Yendor take 1 each.CodeNetHack 3.6.7 sourcerevised
   How we know

   119    u.uhunger = 900;
   

   176                    /* once-per-turn things go here */
   

   281                    gethungry();
   

   2799    if ((!Unaware || !rn2(10)) /* slow metabolic rate while asleep */
   

   2821        switch ((int) (moves % 20)) { /* note: use even cases only */
   

   373#define Unaware (multi < 0 && (unconscious() || is_fainted()))
   

   25    SLT_ENCUMBER = 1, /* Burdened */
   

   1873    if (p_type == 3 && !Inhell) {
   ⋮
   1877        u.uinvulnerable = TRUE;
   

   1978overexertion()
   ⋮
   1983    gethungry();
   

   408        || overexertion())
   409        goto atk_done;
   

   Checked against the evidence by its author, an AI model, 2026-10-25.

   Revised after a check by a second AI model, 2026-10-21.

   Checked by a second AI model, 2026-10-25.

   In the claim ledger

3. ^Rogue 5.4 starts the hero with 1,300 food. The stomach daemon runs once per pass of the command loop, after the hero's move, or after both moves when the hero is hasted. While food is above 0 it takes 1, plus each worn ring's cost, and 1 less while the hero carries the Amulet of Yendor, so with the Amulet and no rings the count stops.CodeRogue 5.4.4 source
   How we know

   29    food_left = HUNGERTIME;
   

   117#define HUNGERTIME	1300
   

   150    start_daemon(stomach, 0, AFTER);
   

   32    if (on(player, ISHASTE))
   

   444    do_daemons(AFTER);
   

   163	food_left -= ring_eat(LEFT) + ring_eat(RIGHT) + 1 - amulet;
   

   148	amulet = TRUE;
   

   Checked against the evidence by its author, an AI model, 2026-10-21.

   Checked by a second AI model, 2026-10-21.

   In the claim ledger

4. ^NetHack 3.6.7 counts the hero Satiated above 1,000 nutrition, Not Hungry above 150, Hungry above 50, Weak above 0, and Fainting at 0 or below. While Fainting, a hero not already fainted or helpless faints on entering the state, and later at a chance that grows as nutrition falls (1 in 20 at 0), for 10 turns plus a tenth of the deficit; on an update where neither happens, the hero starves once nutrition is below −(100 + 10 × Constitution).CodeNetHack 3.6.7 source
   How we know

   2939                            : (h > 50) ? HUNGRY : (h > 0) ? WEAK : FAINTING;
   

   2983        if (u.uhs <= WEAK || rn2(20 - uhunger_div_by_10) >= 19) {
   

   3004        } else if (u.uhunger < -(100 + 10 * (int) ACURR(A_CON))) {
   

   2842    newuhs(TRUE);
   

   Checked against the evidence by its author, an AI model, 2026-10-21.

   Checked by a second AI model, 2026-10-21.

   In the claim ledger

5. ^Eating any food in Rogue 5.4 first raises a negative count to 0, then adds 1,100 to 1,499 (HUNGERTIME - 200 + rnd(400)), capped at 2,000.CodeRogue 5.4.4 source
   How we know

   298    if ((food_left += HUNGERTIME - 200 + rnd(400)) > STOMACHSIZE)
   

   119#define STOMACHSIZE	2000
   

   Checked against the evidence by its author, an AI model, 2026-10-21.

   Checked by a second AI model, 2026-10-21.

   In the claim ledger

6. ^In NetHack 3.6.7, food that brings nutrition to 2,000 or more chokes a hero who was Satiated (for a meal, at its start). A hero who doesn't breathe always vomits and loses 1,000 nutrition instead; a hero being strangled always dies; any other hero vomits 1 time in 20 and otherwise dies.CodeNetHack 3.6.7 sourcerevised
   How we know

   2864    if (u.uhunger >= 2000) {
   

   2543        context.victual.canchoke = (u.uhs == SATIATED);
   

   252    if (Breathless || (!Strangled && !rn2(20))) {
   

   Checked against the evidence by its author, an AI model, 2026-10-21.

   Revised after a check by a second AI model, 2026-10-21.

   In the claim ledger

7. ^Computed from both games' code, NetHack 3.6.7's melee roll keeps the rate of Rogue 5.4's swing: each point of the attacker's level or the target's armor class adds 5% to the chance to hit, which is (level + armor class + bonuses) / 20 in Rogue and (level + armor class + Luck + bonuses) / 20 in NetHack.CodeNetHack 3.6.7 source · Rogue 5.4.4 sourcerevised
   How we know

   266    tmp = 1 + Luck + abon() + find_mac(mtmp) + u.uhitinc
   

   613    int mhit = (tmp > dieroll || u.uswallow);
   

   172    x = RND(x) + 1;
   

   381    int need = (20 - at_lvl) - op_arm;
   

   188    return range == 0 ? 0 : abs((int) RN) % range;
   

   Checked against the evidence by its author, an AI model, 2026-10-21.

   Revised after a check by a second AI model, 2026-10-21.

   In the claim ledger

8. ^An ordinary NetHack 3.6.7 level places rooms, one of which may be a vault, in free rectangles until none is left, a room fails to fit, or it has 40. It sorts them by left edge, and joins each to the next, stopping early at a chance of 1 in 50 per join. It then joins each room to the one two along when they aren't yet connected, then any pair still unconnected. With 3 or more rooms it makes 4 to (room count + 3) attempts at another corridor; an attempt gives up before digging when the square outside its door is already open, and stops short, leaving a dead end, at a chance of 1 in 35 per step.CodeNetHack 3.6.7 sourcerevised
   How we know

   229    while (nroom < MAXNROFROOMS && rnd_rect()) {
   

   330#define MAXNROFROOMS 40 /* max number of rooms per level */
   

   62    if (x->lx < y->lx)
   

   704    sort_rooms();
   

   341        for (i = rn2(nroom) + 4; i; i--) {
   

   294    if (nxcor && levl[xx + dx][yy + dy].typ)
   

   2248        if (cct++ > 500 || (nxcor && !rn2(35)))
   

   Checked against the evidence by its author, an AI model, 2026-10-21.

   Revised after a check by a second AI model, 2026-10-21.

   In the claim ledger

9. ^NetHack 3.6.7's main dungeon, the Dungeons of Doom, holds one level built in Rogue's style. Its code's comment says “Rogue levels are structured 3 by 3, with each section containing a room or an intersection”, and each of the nine cells is an intersection at a chance of 1 in 5, so long as at least one room is made.CodeNetHack 3.6.7 source
   How we know

   20LEVEL:		"rogue" "R" @ (15, 4)
   

   Rogue levels are structured 3 by 3, with each section containing

   233            if (!rn2(5) && (nroom || (x < 2 && y < 2))) {
   

   700        makeroguerooms();
   

   Checked against the evidence by its author, an AI model, 2026-10-21.

   Checked by a second AI model, 2026-10-21.

   In the claim ledger

10. ^When a NetHack 3.6.7 hero dies, unless a worn amulet of life saving or the wizard and explore modes' “Die?” prompt saves the hero, the game records the score and ends the program.CodeNetHack 3.6.7 sourcerevised
    How we know

    1201    really_done(how);
    

    1626    nh_terminate(EXIT_SUCCESS);
    

    Checked against the evidence by its author, an AI model, 2026-10-21.

    Revised after a check by a second AI model, 2026-10-21.

    In the claim ledger

11. ^Restoring a NetHack 3.6.7 game deletes the save file once it is read, unless the game is in wizard (debug) or explore mode; in those modes the Unix build asks “Do you want to keep the save file?”. While a restore runs, the Unix build makes the file unreadable, to disallow parallel restores.CodeNetHack 3.6.7 source
    How we know

    901    if (!wizard && !discover)
    

    295        (void) chmod(fq_save, 0); /* disallow parallel restores */
    

    312                if (yn("Do you want to keep the save file?") == 'n') {
    

    Checked against the evidence by its author, an AI model, 2026-10-21.

    Checked by a second AI model, 2026-10-21.

    In the claim ledger

12. ^When a NetHack 3.6.7 hero dies in wizard (debug) or explore mode, from any cause of death from an ordinary death to genocide (not a panic, quitting, escaping, or ascending), and a worn amulet of life saving hasn't already saved the hero, the game asks “Die?”; answering no saves the hero's life and play goes on.CodeNetHack 3.6.7 sourcerevised
    How we know

    1188    if (!survive && (wizard || discover) && how <= GENOCIDED
    1189        && !paranoid_query(ParanoidDie, "Die?")) {
    ⋮
    1192        savelife(how);
    1193        survive = TRUE;
    

    1168    if (Lifesaved && (how <= GENOCIDED)) {
    

    148    GENOCIDED    = 10,
    

    Checked against the evidence by its author, an AI model, 2026-10-25.

    Revised after a check by a second AI model, 2026-10-21.

    Checked by a second AI model, 2026-10-25.

    In the claim ledger

13. ^When a NetHack 3.6.7 game starts, it shuffles the descriptions of amulets, potions, rings, scrolls, spellbooks, wands, and venoms within each class, and of helmets, gloves, cloaks, and boots within each of those groups. Water keeps a fixed description, and scrolls, spellbooks, and amulets keep the unique or non-magic ones fixed; a type whose name is already known keeps its description.CodeNetHack 3.6.7 source
    How we know

    179    shuffle_all();
    

    247        AMULET_CLASS, POTION_CLASS, RING_CLASS,  SCROLL_CLASS,
    

    88        if (objects[j].oc_name_known)
    

    208    case POTION_CLASS:
    ⋮
    211        *hi_p = POT_WATER - 1;
    212        break;
    ⋮
    219            if (objects[i].oc_unique || !objects[i].oc_magic)
    220                break;
    221        *hi_p = i - 1;
    

    Checked against the evidence by its author, an AI model, 2026-10-25.

    Checked by a second AI model, 2026-10-21.

    Checked by a second AI model, 2026-10-25.

    In the claim ledger