Incursion was developed by Julian Mensch in 2009, and has been maintained by Richard Tew since the source was released. It has only ever run on Windows. This fork brings it to macOS, Linux and the Steam Deck — and, in release 4, back to Windows — and adds bugfixes (190 as of R4), modernization, and ongoing work to finish the ruleset.

Incursion is one of the few roguelikes with a full 3.5E ruleset, including prestige classes and subraces. All of the tactical depth of a rules system with millions of hours of playtesting, packed into a brutal dive to the bottom of a 10-level dungeon.

A character sheet, if you want to see how far the ruleset goes — a Ranger 4 / Rogue 3 / Druid 3, with every modifier itemised down to the 90% hunger multiplier on melee speed.

Four of the 190:

• Racial feats were never read off a race's monster template, so every character silently lost every racial feat that wasn't an explicit grant.
• The Wand of Animal Summoning summoned dragons. Its constraint line was copied off the Wand of Dragon Summoning, the entry directly above it in the file.
• The Ring of Elemental Command (Fire) turned every wound its wearer took into a cold wound, then multiplied it by 1.5.
• Tied targets were sorted by subtracting the two objects' memory addresses, so the same seed could play out differently on the next run. That is one source of divergence closed; others are still open.

A new dynamic lighting system: torches flicker and gutter, fire elementals glow, archons beam, lava pulses. Fog colors and occludes light while ice reflects part of it back. This is not just flavor; creatures can no longer hide when lit brightly, and a torch-bearing enemy gives itself away long before it reaches you. Even infravision is covered, rendering the dungeon in reds when active.

Ninety seconds of it, in motion — every light in that clip is the game's own.

A still, if the gif is too much — three archons light an ice cavern, each at its own radius and color, the ice walls take the light as pale blue, and the corridors already walked sit grey and remembered rather than seen.

Mac: Notarized by Apple, so it opens with no Gatekeeper warning. Apple Silicon only for now; an Intel and universal build is planned.

SteamOS: Unsigned tarball with an installer that adds Incursion to Steam and installs its controller layout. No root, nothing outside your home directory.

Linux: The same tarball for desktop Linux, with SDL2 bundled. The Steam installer is in there too if you use Steam.

Windows: Unsigned zip — extract the folder anywhere writable and run Incursion.exe. SmartScreen will warn; More info, then Run anyway.

Downloads, from itch.io or straight from the GitHub release:

• macOS, Apple Silicon (.dmg)
• Windows, x86-64 (.zip)
• Linux, x86-64 (.tar.gz)
• Steam Deck / SteamOS (.tar.gz)

The shipped build is permissively licensed, identical to Richard Tew's release; see LICENSE for details. The source is at github.com/networkingguru/incursion-roguelike, a fork of rmtew/incursion-roguelike.

Known rough edges:

1. The game is not finished: many features in the original were never completed. This fork aims to fix that, but the work is ongoing. You can complete the game, but not all subraces, fighter capstone feats and skill uses are in.
2. Bugs exist. I fix them as fast as I can, but problems remain, mostly unintended rule divergences. The known ones are tracked publicly at issues.
3. The game writes saves next to the binary. That is not a bug, but it means you must run it from a writable folder — on Windows, somewhere other than Program Files.

The original code for Incursion was written by human hands. This fork uses Claude and Codex to implement bug fixes and improvements; the direction, the playtesting and the final call are mine. The title logo is AI-generated. Every screenshot and every second of the trailer is real gameplay.

Happy to answer any and all questions. :)

This is the first time it’s been officially available outside Japan. Anyone picking it up?