Infra Arcana

A roguelike after H. P. Lovecraft · into the lair of the Church of Starry Wisdom, for the Shining Trapezohedron

Date of birth2011 1.0 on 5 June 2011 (dev logs from August 2010); this build 23.0.0, 18 May 2025

CreatorMartin Törnqvist 2010 to today, tiles by Oryx

LanguageC++17 ~123,000 lines, SDL2

PlatformWindows, Linux SDL window, tiles or ASCII

Lineage

No parent: Infra Arcana is an original game in its own C++ code, not a variant of any other roguelike. RogueBasin names its influences as H. P. Lovecraft, horror movies and the PC shooter Blood. Development logs start in August 2010 under another name; 1.0 came out on 5 June 2011 and the game is still developed (23.0.0 on 18 May 2025, 23.1.0 in progress). It has no known descendants.

See the family tree (among the standalone originals). Sources: RogueBasin, release_history.txt, the source on GitLab.

Credits

Martin Törnqvist	Design, code and writing, 2010 onwards
Oryx	(Christopher Barrett, Oryx Design Lab) the tile set, maintained long after the first draft
Agata Skrzypczyk	Logo and icon
Renan Nunes	Rewrote many monster descriptions, gameplay ideas
Ideas	Kornel Dabrowiecki, Paul Onyschuk
Music	Musica Cthulhiana, “Madness” from the album Fragment (main menu, by permission)
Sounds	Mostly from freesound.org, each credited in `LICENSE-AUDIO.txt`
Web port	This page’s browser build: memmaker/ia

From the game’s credits.txt, contact.txt and LICENSE-AUDIO.txt.

Trivia

The changelog ends with “Old changelogs from before the game was named Infra Arcana”, reaching back to 25 August 2010 (dynamite, reloading, the Phantasm). (release_history.txt)
Versions 1.0 to 11.2 all came out in 2011: eleven major releases in the first seven months. (release_history.txt)
Very early builds had bouncing thrown items; they were removed because they “felt too unpredictable”. (release_history.txt)
In 14.1 the manual became a plain .txt file “conveniently readable externally”. (release_history.txt)
The Insanity chapter of the manual opens with a long quote from Lovecraft’s “The Rats in the Walls”. (manual)
RogueBasin singles out its “excellent use of spooky ambient sounds”. (RogueBasin)

What's unique

1920s horror: pitchforks, sawn-off shotguns, Tommy guns, dynamite and an electric lantern against cultists, ghouls, Deep Ones and Mi-Go.
Shock, not hunger: seeing horrors, darkness and occult power raise shock; at 100% you scream, faint or gain a phobia and insanity rises. Going down a level resets shock.
No XP for kills: experience comes from discovering items and monsters and from descending, so sneaking past is a real strategy (and backstabs are deadly).
Wounds: big hits leave wounds that don't heal on their own; a medical bag treats wounds and infections; five wounds kill.
Spirit: spells from manuscripts can be memorised and cast, but they cost spirit, and running out of spirit kills you.
One way down: no up stairs; every level is a step closer to the Trapezohedron.

Code dive

Language: C++17, about 123,000 lines in 328 files under src/ and include/ at upstream a084376; built with CMake on SDL2, SDL2_image and SDL2_mixer. Licence AGPL-3.0-or-later.
Data: monsters live in data/monsters.xml (with their tile and colour), colours in XML, fixed levels (the intro forest, Egypt, the Mi-Go outpost, the High Priest) as text maps; items, spells and traits are C++ tables.
Test bot: --bot and --stress-test let the game play itself.
This port: the game’s own SDL2 code compiled with Emscripten; status, messages, inventory and visible monsters in separate windows, menus as HTML text, saves in IndexedDB, an Enter command menu, X explore and > walk to the stairs. Source: memmaker/ia, upstream martin-tornqvist/ia.

Stats

Thing	Count	Notable ones
Levels	30	early game 1–9, mid game 10–19, late game 20–30; special levels: Egypt, Rat cave, Deep One lair, Magic pool, Mi-Go outpost, the High Priest, the Trapezohedron
Monsters	105	Keziah Mason and Brown Jenkin, Richard Upton Pickman, Major Clapham-Lee, Dean Halsey, Khephren, Nitokris, Zuul the Gatekeeper, The Omega Sentinel, a Strange Color, Leviathan
Backgrounds	6	War Veteran, Rogue, Ghoul, Occultist, Exorcist, Flagellant
Traits	68	Treasure Hunter, Ravenous, Memento Mori, Undead Bane, Galvanization
Spells	52	7 domains: Channeling, Corruption, Illusion, Mind, Time, Warding, Blood; Crimson Passage, Projected Strike, Temporal Echo, Mirror Images
Items	162	item types incl. intrinsic attacks; 9 curses (Shriek, Light sensitive, Cannot read)
Properties	117	status effects and resistances
Insanity	19	symptoms: babbling, sadism, paranoia, phobias of dogs, the dark, the dead, the deep, rats, reptiles, spiders
Traps	15	7 mechanical (spear, web, alarm), 8 sigils (unlearn spell, alter environment)

Counted from include/*.hpp enums, global.hpp and data/monsters.xml at a084376.

Manual

The game’s own manual (manual.txt, also in the main menu), the full release history back to 2010 and the credits. Licence: AGPL-3.0-or-later (LICENSE.txt).

Getting started

Open the game, choose New journey, a background and a trait.
Explore with X; > walks to the stairs you have seen, a second > descends (there is no way back up).
Fight with f (aim/fire), r reloads, z swaps to the prepared weapon; light dynamite from a and throw it with t.
Watch Shock and Insanity in the status window; keep your lantern on and descend before shock builds up. Treat wounds with the medical bag.
The Enter key lists every command; read the game’s help page for keys and saving (the game saves when you descend).

Help

We found no walkthrough or strategy guide. Rules of thumb from the game’s own manual and RogueBasin:

You get no experience for kills: sneak past what you don't need to fight, and backstab unaware monsters.
Descend steadily: shock resets on every new level, and dwelling raises it.
Treat infections early, before they turn into a permanent disease.
Casting from memory costs spirit; the game warns when a cast could kill you.
More: the manual, RogueBasin, r/InfraArcana and the game’s site.

Cheats

Debug builds have F2–F10 cheat keys (next level, +100 XP, cheat vision, +50 shock, spawn monsters or items, teleport), compiled only without NDEBUG in game_commands.cpp. This build uses -DNDEBUG, so they are gone. No wizard mode, no cheat options.

Save scumming: Export save / Import save on the game page (the game saves once per level).