Netwhack as an ode to Rogue, Hack and Nethack (Part 1)

Disclaimer: I’m rambling, and this is all just opinion and speculation, not legal fact (except where it happens to actually be true).

What is the future of Nethack? Way back in 1997 I had wanted to make a C++ version of Nethack. As time went by though, my game became further and further away from what Nethack was. At the same time, Nethack itself changed. Version 3.6 brought many structural changes to the game which in my opinion changed the UX (user experience) of the game away, slightly, from the “old ways” of Rogue, Hack, and Nethack 3.x. 3.3 and 3.4.x were some of the finest games of Nethack I had ever played, and to a very large degree gave me hope and inspiration that one day, I could make my own similar game.

Those dreams are mostly gone, in that Nethack itself has changed, and time has changed me, and my game. Netwhack is written in Java, and will ultimately divorce itself from the trends Nethack has followed and attach itself more to the old playstyle of the earlier games.

So here’s the basic gameplan going forward. Rogue was released in the public domain. Therefore, everything in Rogue will be added to Netwhack, subject to revision of course.

Hack is the next step in development. Hack was originally a Rogue clone, then later improved. Hack was released under the BSD three clause license in the early 80s. Since I am not using the source code at all, I do not need to include the BSD license as there is no modified code at all in my release. In return, I am barred from using the name Hack to endorse my program. I.E. I can call it a roguelike, but I can’t call it a Hacklike or say it’s based on hack in promo material.

Then there are intermediaries. These are described in Nethack’s Game History [local archive]:

Mike Stephenson merged these various versions back together, incorporating many of the added features, and produced NetHack version 1.4. He then coordinated a cast of thousands in enhancing and debugging NetHack 1.4 and released NetHack versions 2.2 and 2.3.

Later, Mike coordinated a major rewrite of the game, heading a team which included Ken Arromdee, Jean-Christophe Collet, Steve Creps, Eric Hendrickson, Izchak Miller, Eric S. Raymond, John Rupley, Mike Threepoint, and Janet Walz, to produce NetHack 3.0c. The same group subsequently released ten patch-level revisions and updates of 3.0. “

By “various versions” the Nethack Guidebook is referring to various versions of Hack. Including then the original rogue, the roadmap to Nethack 2.2 and 2.3 is apparently to merge various public domain and BSD-licensed software into a single game. This would necessitate ideas being taken moreso than code, since most of the code was de facto the hack 1.0.3. codebase.

It would then seem that the Nethack GPL does not really protect code prior to Nethack 3.0, since prior to Nethack 3.0 — assuming the rewrite was sufficient to remove the BSD license — all of Nethack was simply BSD and public domain code squished together.

If you took two Beethoven symphonies and squished them together, could you copyright it? No.

This lets us use very early versions of Nethack, and other PD and BSD-licensed sources to create a sort of ‘roadmap’ for Netwhack. This will essentially be represented by Michael Toy’s paper on rogue, followed by the changelog for Hack and Nethack up to Nethack 2.3 — minus any truly original content, such as exactly reproducing a special level.

Let’s take a wild stab here and include all of that information right now. We can revise this later, but this will be the general idea.

1. Michael Toy’s paper on Rogue



2. Hack

From Jay Fenlason’s PD Hack to Andries Brouwer’s BSD-licensed Hack 1.0:

  • The concept of a role was introduced in Hack 1.0, and is not present in the other versions. Hack121 begins with a screen from which the player may buy equipment, this is mentioned by Robert Grover as a feature of Fenlason’s original version. Brouwer presumably removed this screen fairly early on: PDP-11 Hack, being derived from an early draft of Andries Brouwer’s Hack, starts the player off as a generic fighter character.
  • The exact goal of the adventurer is uncertain. The Amulet of Yendor is not mentioned.
  • Hack121 does not have pets. PDP-11 Hack starts the player off with a little dog, suggesting that pets were a relatively early addition by Brouwer.
  • It seems likely that shops were the only special room type in Fenlason’s original code.
  • Hack121 has shops. No other special room types are presently known to exist in hack121.
  • PDP-11 Hack has shops (mkshop), zoos (mkzoo), graveyards (mkyard), swamps (mkswamp) and vaults (mk_knox). The developers of PDP-11 Hack, per their readme, implemented vaults, swamps, zoos and graveyards themselves, leaving shops as the only roomtype which was present in the sources they originally obtained. Vaults, in particular, are implemented very differently to Hack 1.0.
  • Hack 1.0 has vaults (not delegated), shops (mkshop) and zoos (mkzoo).


Hack Main monster list

These are given in the order of their appearance in the code; it will be seen that the lists are quite similar.

Hack121 PDP-11 Hack Hack 1.0
bat (b) bat (B) bat (B)
lizard (l) gnome (G) gnome (G)
goblin (g) hobgoblin (H) hobgoblin (H)
jackal (j) jackal (J) jackal (J)
kobold (k) kobold (K) kobold (K)
pickpocket (p) leprechaun (L) leprechaun (L)
giant rat (r) giant rat (r) giant rat (r)
acid blob (a) acid blob (a) acid blob (a)
evil eye (e) floating eye (E) floating eye (E)
hurkle (h) homunculus (h) homunculus (h)
neevil (n) imp (i) imp (i)
orc (o) orc (O) orc (O)
yellow light (y) yellow light (y) yellow light (y)
zombie (z) zombie (Z) zombie (Z)
giant ant (A) giant ant (A) giant ant (A)
fog cloud (f) fog cloud (f) fog cloud (f)
robber (R) nymph (N) nymph (N)
stalactoid (s) piercer (p) piercer (p)
queevolt (q) quasit (Q) quasit (Q)
quivering blob (Q) quivering blob (q) quivering blob (q)
grabber (G) violet fungi (v) violet fungi (v)
nepto (N) giant beetle (b) giant beetle (b)
centaur (c) centaur (C) centaur (C)
cockatrice (C) cockatrice (c) cockatrice (c)
ghost (‘) gelatinous cube (g) gelatinous cube (g)
jaguar (J) jaguar (j) jaguar (j)
killer bee (K) killer bee (k) killer bee (k)
viper (v) snake (S) snake (S)
ice ball (i) freezing sphere (F) freezing sphere (F)
giant bear (B) owlbear (o) owlbear (o)
oxidizer (O) rust monster (R) rust monster (R)
unox (u) giant scorpion (s) scorpion (s)
teleporter (t) teleporter (t) tengu (t)
wraith (w) wraith (W) wraith (W)
snowman (S) long worm (w) long worm or wumpus (w)
octopus (0) large dog (d) large dog (d)
xyloman (x) leocrotta (l) leocrotta (l)
faker (F) mimic (M) mimic (M)
minotaur (m) minotaur (m) found at end of table
troll (T) troll (T) troll (T)
ugod (U) ugod (u) unicorn (u)
xerp (X) yeti (Y) yeti (Y)
phase shifter (P) invisible stalker (I) stalker (I)
hydra (H) umber hulk (U) umber hulk (U)
vampire (V) vampire (V) vampire (V)
wumpus (W) xorn (X) xorn (X)
rock lobster (L) xerp (x) xan (x)
zelomp (Z) zruty (z)
chameleon (:) chameleon (:) chameleon (:)
dragon (D) dragon (D) dragon (D)
energar (E) ettin (e) ettin (e)
floor fiend (;) lurker above (‘) lurker above (~)
landshark (&) neo-otyugh (n) nurse (n)
argus (}) trapper (,) trapper (,)
mega-worm (M) purple worm (P) purple worm (P)
demon (d) demon (&) demon (&)
minotaur (m)
shopkeeper (@)


in the same row. The large dog appears both here and in the above table because the structure in the above table is used for wild dogs, and the one shown below is used for pets. In Hack 1.0, the shopkeeper is moved to the main monster list.

Hack121 PDP-11 Hack Hack 1.0
vampire bat (b)
shopkeep (☺) shopkeeper (@) in main monster table
guard (☺) treasurer (@) guard (@)
little dog (d) little dog (d)
dog (d) dog (d)
large dog (d) large dog (d)
giant eel (;)
ghost (tab)



Hack121 takes a different approach to armor than the other two Hacks. The only actual armors are suits. A shield is implemented but is a distinct type of object, in a class by itself. However, note that a shield is put on using the same command used to put on armor and affects your armor class rating in the same way that other armor does. PDP-11 Hack implements only suits and an elven cloak. Hack 1.0 adds a helmet, a shield, and a pair of gloves, allowing five pieces of armor to be worn at the same time.

The list of hack121 suits is reordered here to match the PDP-11 and Hack 1.0 orders.

Hack121 PDP-11 Hack 1.0
plate mail plate mail plate mail
splint mail splint mail splint mail
banded mail banded mail
chain mail chain mail chain mail
scale mail scale mail scale mail
ring mail ring mail ring mail
studded leather armor studded leather armor
leather armor leather armor leather armor
elven cloak elven cloak
elfin chain mail
(not armor) shield
pair of gloves


The available food items are as follows:

Hack121 PDP-11 Hack 1.0
food ration food ration food ration
tripe ration tripe ration tripe ration
beef jerky pancake pancake
dead lizard dead lizard dead lizard
steak cookie fortune cookie
orange orange orange
apple apple apple
pear pear pear
melon melon
banana banana banana
spinach candy bar candy bar
egg egg egg
clove of garlic

As Hack121 does not appear to have pets, it is unclear why the first five items are all meat.

The dead lizard has no special properties in PDP-11 Hack. Its function in hack121 is just as an item of food. It has no other special functions. In Hack 1.0, it can relieve confusion, but has no effect on cockatrices: stoning by cockatrice hissing is an instadeath in all three of these versions of Hack. Both spinach and steak may randomly increase strength in hack121.


Hack121 and PDP-11 Hack offer the same set of weapons. Hack 1.0 adds a few to these:

hack121 PDP-11 Hack 1.0
arrow arrow arrow
sling bullet sling bullet sling bullet
crossbow bolt crossbow bolt crossbow bolt
dart dart dart
mace mace mace
axe axe axe
flail flail flail
long sword long sword long sword
two handed sword two handed sword two handed sword
dagger dagger dagger
worm tooth
spear spear spear
bow bow bow
sling sling sling
crossbow crossbow crossbow


Several potions in Hack121 have disappeared in later versions. Hack 1.0 adds one potion over PDP-11.

Hack121 PDP-11 PC/IX Hack 1.0
restore strength restore strength restore strength restore strength
alcohol booze confuse monster booze
second sight
extra hit points
invisibility invisibility invisibility invisibility
fruit juice fruit juice fruit juice fruit juice
healing healing healing healing
paralysis paralysis paralysis paralysis
monster detection monster detection monster detection
object detection object detection object detection object detection
poison sickness sickness sickness
confusion confusion confusion confusion
gain strength gain strength gain strength
speed speed speed speed
blindness blindness blindness blindness
gain level gain level gain level gain level
extra healing extra healing extra healing extra healing

‡ PDP-11 Hack replaced the scroll of confuse monster with a scroll of losing. The porters to PC/IX reinstated the former as a potion.


Available scrolls are as follows. The Hack121 list is ordered in an attempt to match the other two.

hack121 PDP11 Hack 1.0
enchant armor enchant armor enchant armor
(different location) (different location) destroy armor
confuse monster losing confuse monster
destroy monsters
scare monsters curse levels scare monster
ressurection [sic]
blank paper
remove curse remove curse remove curse
enchant weapon enchant weapon enchant weapon
create monster create monster damage weapon
damage weapon damage weapon create monster
genocide genocide genocide
rust armor destroy armor (different location)
light light light
teleportation transportation teleportation
gold detection gold detection gold detection
food detection
identify identify identify
magic mapping magic mapping magic mapping
fire fire fire
charge wand

For PDP-11 Hack:

  • The “scroll of losing” takes away the hero’s entire inventory and scatters it about the level. It is noted in source code comments as replacing the scroll of confuse monster.
  • The “scroll of curse levels” appears to curse the hero himself, causing shopkeepers to be angry and all picked-up items to become cursed. The scroll of remove curse will rescind this effect, and in these versions it is not itself affected by curses.
  • The scroll of transportation, as well as teleporting, functions as an elevator. The code carries the notice “Extended by Michiel and Fred: One can jump between levels”.


Available wands are as follows. The Hack121 list is reordered in an attempt to match the other two:

Hack121 PDP-11 Hack 1.0
light light light
trap detection secret door + trap detection secret door detection
create monster create monster create monster
striking exhaustion striking
slow monster slow monster slow monster
speed monster speed monster speed monster
undead turning undead turning
polymorph polymorph polymorph
frighten monster
cancellation cancellation cancellation
teleport monster teleport monster teleport monster
make invisible
digging digging digging
monster invisibility
magic missile magic missile magic missile
fire fire fire
sleep sleep sleep
cold cold cold
death death death
door closing

In Hack121, the wand of wonder is a random wand of another type which changes each time you zap it. In D&D, a wand of wonder works as a random wand of another type.

Note: In iLarn (and in ULarn), a wand of wonder prevents the player from falling down holes when in the main inventory. It could serve the same purpose here, as this would not be very apparent to most players.


Available rings are as follows. For hack121, the order has been changed to match the other two versions.

Hack121 PDP-11 Hack 1.0
adornment adornment adornment
teleportation teleportation teleportation
regeneration regeneration regeneration
searching searching searching
see invisible see invisible see invisible
stealth stealth stealth
floating levitation
poison resistance poison resistance poison resistance
aggravate monster aggravate monster aggravate monster
hunger hunger hunger
monster creation
another chance
fire and cold resistance fire resistance fire resistance
cold resistance cold resistance
protection from magic protection from shape-changers protection from shape changers
gain strength gain strength gain strength
increase damage increase damage increase damage
protection protection protection
increase hit points
teleport control

It is uncertain if the hack121 ring of protection from magic has any connection to the ring of protection from shape changers in the other versions.


Hack121 appears to have gems, but their function is uncertain. In PDP-11 Hack, they only add to the player’s score; neither of these Hacks has unicorns. Hack 1.0 has gems in their modern form.

Other objects

The remaining objects in each game seem to have no connection to each other. Hack121 has these objects:

PDP-11 Hack has only the “amulet of Frobozz”, which may be the forerunner of the Amulet of Yendor.

Hack 1.0 has these objects:

Hack 1.0 Inventory


The following monsters may be encountered:

Name Symbol Notes
acid blob a
bat B
centaur C
chameleon :
cockatrice c Stoning by hissing is an instadeath
demon &
dog d
dragon D As the modern red dragon
ettin e
floating eye E
fog cloud f
freezing sphere F
gelatinous cube g
ghost (space)
giant ant A
giant beetle b
giant rat r
gnome G
guard @
hobgoblin H
homunculus h
imp i
jackal J
jaguar j
killer bee k
kobold K
large dog d
leocrotta l
leprechaun L
little dog d
long worm w if NOWORM not defined at compile time
lurker above ~
mimic M
minotaur m
nurse n
nymph N
orc O
owlbear o
piercer p
purple worm P
quasit Q
quivering blob q
rust monster R Reduces enchantment rather than truly rusting
scorpion s
shopkeeper @
snake S
stalker I
tengu t
trapper ,
troll T
umber hulk U
unicorn u
vampire V
violet fungi v
wraith W
wumpus w if NOWORM defined at compile time
xan x
xorn X
yellow light y
yeti Y
zombie Z
zruty z



Hack 1.0 has only one artifact, Orcrist. Any weapon may be named Orcrist and will do d10 extra points damage to orcs. There can even be more than one Orcrist.

In Hack 1.0.2, Orcrist would be limited to two handed swords.


Only the Amulet of Yendor and the cheap plastic imitation exist in Hack 1.0.


Food items in Hack 1.0 are:

The tin did not contain the remains of monsters, but rather a randomly-chosen food such as peaches or, if the adventurer is lucky, spinach.

The dead lizard was a found object rather than a corpse; live lizards did not exist in Hack 1.0. It could reduce confusion, but had no effect on cockatrices.


Weapons in Hack 1.0 are:


Tools in Hack 1.0 are:

The ice box is the only container. Then as now, it preserved corpses, and was generally too heavy (and too rare) to be useful for inventory management.


Armor items in Hack 1.0 are:


Potions in Hack 1.0 are:


Scrolls in Hack 1.0 are:

The scroll of damage weapon acts as the modern scroll of enchant weapon does when cursed. The scroll of genocide acts, in all cases, as the modern blessed scroll; but most symbols refer to only one monster anyway.


Wands in Hack 1.0 are:


Rings in Hack 1.0 are:

Because charisma does not exist in Hack 1.0, the ring of adornment is a useless item.


Gems in Hack 1.0 are:

and worthless pieces of blue, red, yellow, and green glass.

Other items

Other items not appearing in the above categories are:

It is not possible to pick up an iron chain, nor can they be generated from iron golems, because these do not exist in Hack 1.0.


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