Action Spaces

Overview

MiniHack has a large, structured and context-sensitive action space. We give practitioners an easy way to restrict the action space in order to promote targeted skill discovery. For example, navigation tasks mostly require movement commands, and occasionally, kicking doors, searching or eating. Skill acquisition tasks, on the other hand, require interactions with objects, e.g. managing the inventory, casting spells, zapping wands, reading scrolls, eating comestibles, quaffing potions, etc. In these tasks 75 actions are used.

The actual game of NetHack uses ASCII inputs, i.e., individual keyboard presses including modifiers like Ctrl and Meta. NLE pre-defines 98 actions, 16 of which are compass directions and 82 of which are command actions. T

Specifying the Action Space

The actions used in MiniHack are defined here. The following example shows how to set the action space of the environment to movements towards 8 compass directions with open, kick, and search actions.

from nle import nethack
MOVE_ACTIONS = tuple(nethack.CompassDirection)
NAVIGATE_ACTIONS = MOVE_ACTIONS + (
    nethack.Command.OPEN,
    nethack.Command.KICK,
    nethack.Command.SEARCH,
)
env = gym.make(
    "MiniHack-Corridor-R3-v0",
    actions=NAVIGATE_ACTIONS,
)

Note that using different observation keys can make environments significantly easier or harder.

Possible Actions

Name

Value

Key

Description

EXTCMD

35

#

perform an extended command

EXTLIST

191

M-?

list all extended commands

ADJUST

225

M-a

adjust inventory letters

ANNOTATE

193

M-A

name current level

APPLY

97

a

apply (use) a tool (pick-axe, key, lamp…)

ATTRIBUTES

24

C-x

show your attributes

AUTOPICKUP

64

@

toggle the pickup option on/off

CALL

67

C

call (name) something

CAST

90

Z

zap (cast) a spell

CHAT

227

M-c

talk to someone

CLOSE

99

c

close a door

CONDUCT

195

M-C

list voluntary challenges you have maintained

DIP

228

M-d

dip an object into something

DOWN

62

>

go down (e.g., a staircase)

DROP

100

d

drop an item

DROPTYPE

68

D

drop specific item types

EAT

101

e

eat something

ESC

27

C-[

escape from the current query/action

ENGRAVE

69

E

engrave writing on the floor

ENHANCE

229

M-e

advance or check weapon and spell skills

FIRE

102

f

fire ammunition from quiver

FIGHT

70

F

Prefix: force fight even if you don’t see a monster

FORCE

230

M-f

force a lock

GLANCE

59

;

show what type of thing a map symbol corresponds to

HELP

63

?

give a help message

HISTORY

86

V

show long version and game history

INVENTORY

105

i

show your inventory

INVENTTYPE

73

I

inventory specific item types

INVOKE

233

M-i

invoke an object’s special powers

JUMP

234

M-j

jump to another location

KICK

4

C-d

kick something

KNOWN

92

\

show what object types have been discovered

KNOWNCLASS

96

`

show discovered types for one class of objects

LOOK

58

:

look at what is here

LOOT

236

M-l

loot a box on the floor

MONSTER

237

M-m

use monster’s special ability

MORE

13

C-m

read the next message

MOVE

109

m

Prefix: move without picking up objects/fighting

MOVEFAR

77

M

Prefix: run without picking up objects/fighting

OFFER

239

M-o

offer a sacrifice to the gods

OPEN

111

o

open a door

OPTIONS

79

O

show option settings, possibly change them

OVERVIEW

15

C-o

show a summary of the explored dungeon

PAY

112

p

pay your shopping bill

PICKUP

44

,

pick up things at the current location

PRAY

240

M-p

pray to the gods for help

PREVMSG

16

C-p

view recent game messages

PUTON

80

P

put on an accessory (ring, amulet, etc)

QUAFF

113

q

quaff (drink) something

QUIT

241

M-q

exit without saving current game

QUIVER

81

Q

select ammunition for quiver

READ

114

r

read a scroll or spellbook

REDRAW

18

C-r

redraw screen

REMOVE

82

R

remove an accessory (ring, amulet, etc)

RIDE

210

M-R

mount or dismount a saddled steed

RUB

242

M-r

rub a lamp or a stone

RUSH

103

g

Prefix: rush until something interesting is seen

SAVE

83

S

save the game and exit

SEARCH

115

s

search for traps and secret doors

SEEALL

42

*

show all equipment in use

SEETRAP

94

^

show the type of adjacent trap

SIT

243

M-s

sit down

SWAP

120

x

swap wielded and secondary weapons

TAKEOFF

84

T

take off one piece of armor

TAKEOFFALL

65

A

remove all armor

TELEPORT

20

C-t

teleport around the level

THROW

116

t

throw something

TIP

212

M-T

empty a container

TRAVEL

95

_

travel to a specific location on the map

TURN

244

M-t

turn undead away

TWOWEAPON

88

X

toggle two-weapon combat

UNTRAP

245

M-u

untrap something

UP

60

<

go up (e.g., a staircase)

VERSION

246

M-v

list compile time options

VERSIONSHORT

118

v

show version

WAIT / SELF

46

.

rest one move while doing nothing / apply to self

WEAR

87

W

wear a piece of armor

WHATDOES

38

&

tell what a command does

WHATIS

47

/

show what type of thing a symbol corresponds to

WIELD

119

w

wield (put in use) a weapon

WIPE

247

M-w

wipe off your face

ZAP

112

z

zap a wand

The descriptions are mostly taken from the cmd.c file in the NetHack source code. For a detailed description of these actions, as well as other NetHack commands, we refer the reader to the NetHack guide book.