Ultima IV: Quest of the Avatar

Ultima IV: Quest of the Avatar (Apple II, 1985) has a decompilation, ergonomy-joe/u4-decompiled, and 4 other public projects, including an open-source reimplementation and a full disassembly.

Data checked 2026-10-12 · unbaked registry

ca65 / cc65

Projects

u4-decompiled

DecompMSC/Turbo C81 starspushed 2023-10-05no license

Decompiled source code for the PC version of Ultima IV - Quest Of The Avatar

Decompiled DOS Ultima IV source (playable)

u4remasteredA2

Disassembly6502 source rebuilt from disassembly (ca65)76 starspushed 2025-01-25no licenserelease v1.2.12

Ultima IV Remastered for the Apple II

Bug-fixed 'remastered' Apple II Ultima IV built from reverse-engineered source.

xu4archived

ReimplementationC73 starspushed 2025-06-05GPL-3.0 license

xu4 "Ultima IV Recreated"

Archived (2025)

ultima4-tsnew, unvetted

ReimplementationTypeScript + three.js + Tauri0 starspushed 2026-10-08no license

Ultima IV: Quest of the Avatar reimplemented in TypeScript + three.js + Tauri, from reverse engineering of the DOS release (requires the original game data)

Reimplementation from RE of DOS release (2026-10).

ScummVM (ultima/xeen/mm/kyra engines)covers 62 games

ReimplementationC++2,842 starspushed 2026-10-12GPL-3.0 licenserelease v2026.4.0

ScummVM main repository

ScummVM includes Ultima IV/VI/VIII, Crusader, Might&Magic 1/Xeen, Eye of the Beholder 1/2, Lands of Lore

What you need

You need your own copy of the game: these projects ship code only.

Same toolchain

GameMethodYearStarsLast push

NESSuper Mario Bros.Source releaseMatching decomp+719853.2k2026-10-07 ARCPac-ManSource releaseMatching decomp+519805942026-10-10 ARCWizard of WorSource releaseDisassembly19805142026-09-20 NESTetrisStatic recompReimplementation+319892822026-09-30 NESThe Legend of ZeldaMatching decompStatic recomp+319862752026-10-07 BBCEliteSource releaseDecomp+219844882026-10-10 ARCContraReimplementationDisassembly+119872312026-06-14 SNESEarthBoundMatching decompDecomp+419941832026-10-12

More on Apple II

GameMethodYearStarsLast push

APL2Prince of PersiaSource releaseStatic recomp+419896.9k2026-10-11 APL2Wizardry: Proving Grounds of the Mad OverlordReimplementation19812442026-09-30 APL2Pinball Construction SetSource release19831682013-02-24 APL2Lode RunnerReimplementationDisassembly+11983962026-07-09 APL2Ultima V: Warriors of DestinyMatching decompReimplementation1988802026-10-12 APL2Where in the World Is Carmen Sandiego?Reimplementation1985392026-07-28 APL2DeathlordReimplementation1987292026-09-23 APL2ChoplifterDisassembly1982992024-10-24

GitHub data checked 2026-10-12. Notes are summaries from the research pass; the project pages are the authority.