iNCURSION

Incursion is one of the deepest roguelikes ever written. Not a game with a few D&D words borrowed for flavour — a real, implemented 3.5 ruleset, with feats that combine, classes that branch into prestige paths, and a tactical combat model that pays you back for every rule you actually know. The magic is not even straight 3.5: Mensch threw out the SRD's eight schools and wrote his own eleven, Arcana and Thaumaturgy and Weavecraft among them. He built something enormous and then very nearly finished it.

It has only ever run on Windows. This fork brings it to macOS, to Linux and to the Steam Deck — and, in release 4, back to Windows. 

It is free. There is nothing to buy, here or later.

The map is lit in colour

Incursion draws its map in the sixteen colours the character set gives it, and a lit square used to be no more than a brighter version of its own colour. There is now a light map under the display. Every torch, lantern, magma pool, glowing creature and light spell casts a coloured footprint that falls away with distance, and each source flickers on noise of its own — a torch gutters, a lantern is nearly steady, magma breathes slowly. Light loses strength and colour crossing ice or fog, and it glints off a shiny wall in the colour that struck it.

Light also decides what you can see and what can see you. A creature can no longer hide while carrying a lit torch, and twelve creatures light their surroundings by their own nature rather than by carrying anything at all.

It plays on a gamepad

The Steam Deck build reads a controller directly. The left stick moves in eight directions, the right stick pans the look cursor, and the d-pad carries Kick, Pray, Legend and Run. The help screen names the pad control beside each key whenever a pad is in front of the game. No keyboard is needed.

What you are downloading

• macOS — Apple Silicon, signed and notarised by Apple. Unzip, drag Incursion.app to Applications, double-click. macOS asks once whether you are sure you want to open an app downloaded from the Internet. That prompt is normal. Your saves live in ~/Library/Application Support/Incursion/, so deleting the app leaves them alone.
• Windows — x86-64, Windows 10 or later. Unpack it wherever you like, and run Incursion.exe from inside the folder it makes. There is no installer and nothing to register. The executable is not signed, so Windows SmartScreen calls its publisher unrecognised the first time you run it: choose More info, then Run anyway. Your saves, options and logs stay inside that folder, beside the binary.
• Linux — x86_64. Unpack and run ./run.sh. SDL2 travels with it.
• Steam Deck — the same build, packed for the Deck. Unpack it and run install-steamos.sh; it adds Incursion to your library with the controller layout already mapped.

The Linux and Steam Deck builds are a beta, and they say so. They have had real playtesting on handheld hardware, but expect bugs, and expect that a save may not survive the next build.

Windows is newer still. It is the same engine the other three downloads carry, and it has been played from the title screen into the dungeon — but in one place only, a Windows 11 ARM64 virtual machine, where an x86-64 binary runs under emulation. No native x86-64 Windows machine has run it yet. Please open an issue for whatever you find.

Source, bugs, licence

The full source is on GitHub. Bug reports go in that project's issue tracker, and they are read.

Incursion is by Julian Mensch, with additional concepts and material by Westley Weimer. Copyright 1999–2007 Julian Mensch, 2014 Richard Tew, 2026 Brian Hill. It is released under the Incursion, MIT, BSD 3-Clause, Apache 2.0 and Open Game licences; the full text ships inside every download and in the game's own help.

This port was written with AI assistance. The design decisions, the bug reports and every published claim are the maintainer's; the code was written with a coding agent in the loop and reviewed before it landed. The title logo is AI-generated. Every screenshot and every second of the trailer is real gameplay.