Hi-Res Adventure #1: Mystery House — Ken and Roberta Williams / On-Line Systems, 1980; public-domain edition released by Sierra On-Line in 1987. ScummVM's official download and release note identify this edition as public domain: https://www.scummvm.org/games/ and https://www.scummvm.org/news/20160915/ . Complete original MYSTHOUS.zip and its 143360-byte Apple II disk are unchanged. The embedded public-domain disclaimer and original title/instruction screens are retained. Original program, parser data, puzzles and graphics are on that disk; ScummVM retains its native, manually created Apple II font rendering. These original game resources are not a Leaf remake or DOS release.
Separate ScummVM 2026.3.0 ADL engine with read-only input-stage observations: GPLv3 or later, notices ../scummvm-expansion/NOTICE.txt and complete matching sources ../scummvm-expansion/source/ and ../scummvm/source/. The separately packaged native engine observes whether ADL awaits text or an acknowledgment, so command entry follows the original prompts. Original cached graphics/text are repainted after browser size changes; equal canvas dimensions do not clear the drawable. No parser, puzzle, command, timing or game-data rule changes. Full original native/library source and platform overlays are shared with existing adventures; exact ADL observer sources/build files are in source/. Game data is not relicensed as GPL. Browser adapter, bounded save persistence and presentation by Leaf Arcade, 2026, GPLv3 or later; their source plus fflate MIT notice is in source/.
Commands are ordinary native keyboard input. Menu and Stop enqueue the original main-menu and Quit events. Stop selects a full session exit and omits a second confirmation; written saves stay intact. The command field sends text and Return; Continue sends Return alone. G and Return starts the game after the original intro; I and Return shows original instructions. Empty Return during play toggles original graphics/text mode. SAVE GAME and RESTORE GAME use the engine's native save slot. Ctrl+F5 opens ScummVM's menu; Ctrl+Q quits. Page Pause freezes the native clock and audio. Stop sends native Quit and flushes written files; it does not save an unfinished game automatically. Use SAVE GAME first. Browser storage is optional for session play. Clearing site data removes saves. No server, account, hosted inference or gameplay API is required.