Sierra Creative Interpreter

File:Sierra-Interaction-Magazine---Ad---KingsQuest5.jpg, highlighting the advanced technical capabilities enabled by Sierra's SCI engine.]]Sierra realized AGI (originally developed for the IBM PCjr) was “under-equipped” for the new multimedia era.{{cite web |url=https://www.mobygames.com/group/6528/game-engine-sierras-creative-interpreter-sci/ |title=Game Engine: Sierra's Creative Interpreter (SCI) |website=MobyGames |access-date=3 May 2025 |url-status=live}}

To meet this challenge, Sierra engineer Jeff Stephenson proposed a completely new, object-oriented interpreter.{{cite web |last=Krogtoft |first=Ernst |title=King's Quest – IBM, Tandy, and Beyond |url=https://retro365.blog/2024/04/05/kings-quest-ibm-tandy-and-beyond/ |website=Retro365 |date=5 April 2024 |access-date=3 May 2025}} As he recalls, “AGI was written in such a way that it was going to take a major rework of the entire game engine…and so that’s when I pitched Ken on SCI…let’s go with a whole new language, we’re going to have to rewrite this thing anyway, let’s make things better.”{{cite web |url=https://www.benshoof.org/blog/sci-scripts |title=Sierra Creative Interpreter—Scripts |work=Benshoof.org |date=2023-07-04 |access-date=2025-05-03 |url-status=live}}

The result was SCI (initially called LSCI for Large-model Script Code Interpreter), a virtual “bytecode” engine that could be compiled for any platform. As Roberta Williams explained, SCI was designed as “a virtual machine language which means that it will work on any machine…Each machine format has its own version of SCI. Our games are never IBM conversions.”{{cite web |last=Byron |first=Tom |title=Roberta's Bequest: An Interview with Sierra On‑Line's Roberta Williams |website=START Magazine – Classic Computer Magazine Archive |url=https://www.atarimagazines.com/startv4n8/robertas_bequest.php |date=March 1990 |access-date=3 May 2025 |url-status=live}}

SCI’s design drew on then-modern programming ideas. Stephenson was influenced by Object-Oriented languages like Smalltalk, which he discovered in a 1981 BYTE issue. He rewrote Sierra’s scripting language into a more structured, object-oriented form. As one retrospective notes, “Stephenson completely rewrote the language…going from a simplistically cryptic scripting language to a full-fledged modern programming language reminiscent of C++, incorporating all the latest thinking about object-oriented coding.”{{cite web |last=Maher |first=Jimmy |title=Sierra Gets Creative |url=https://www.filfre.net/2016/08/sierra-gets-creative/ |website=The Digital Antiquarian |date=5 August 2016 |access-date=3 May 2025}} In practical terms, SCI scripts could define classes for rooms, actors, puzzles, etc., making the engine more flexible.

King’s Quest IV (1988) was the first title to employ Sierra’s Creative Interpreter engine, demonstrating the engine’s expanded multimedia support.{{cite journal|last=Greenberg|first=Raz|title=The Animation of Gamers and the Gamers as Animators in Sierra On-Line’s Adventure Games|journal=Animation|publisher=SAGE Publications|volume=16|issue=1-2|pages=83–95|year=2021|doi=10.1177/17468477211025665|url=https://www.researchgate.net/publication/353266870_The_Animation_of_Gamers_and_the_Gamers_as_Animators_in_Sierra-On-Line%27s_Adventure_Games|access-date=3 May 2025}} It featured a full orchestral score by William Goldstein, one of the earliest uses of a Hollywood-style soundtrack in a computer game. These audio enhancements illustrated SCI’s ability to handle more complex musical arrangements and contributed to a more cinematic adventure experience.

SCI was developed in successive versions, each offering technical advancements:

SCI was an interpreted engine using a proprietary scripting language with object-oriented features. It supported platforms including MS-DOS, Windows, Macintosh, Amiga, and FM Towns.

Graphics support ranged from 16-color EGA in SCI0 to 256-color SVGA in SCI2/SCI3. SCI also supported a variety of sound hardware, including AdLib, Sound Blaster, and Roland MT-32.{{cite web |title=King's Quest V Manual |url=https://www.abandonwaredos.com/docs.php?sf=king_s_quest_v_manual.txt&st=manual&sg=King%27s+Quest+V%3A+Absence+Makes+the+Heart+Go+Yonder%21&idg=481 |website=Abandonware DOS}}

• King’s Quest IV-VII
• Space Quest III-VI
• Leisure Suit Larry II-VII
• Police Quest II-IV
• Quest for Glory I-IV
• Gabriel Knight I-II
• Phantasmagoria I-II
• Freddy Pharkas: Frontier Pharmacist
• EcoQuest I-II

SCI was one of the leading adventure game engines of its time, alongside LucasArts' SCUMM. It influenced modern engines like Adventure Game Studio. Preservation efforts include support for SCI games in ScummVM, which merged with the FreeSCI project in 2009.{{cite web |title=ScummVM Adds Support for Sierra Classics |url=https://www.linux.com/news/scummvm-adds-support-sierra-classics/ |website=Linux.com}}

{{Reflist}}

• {{YouTube|id=K3s0nW1FBN8|title=Interview with SCI engineer Jeff Stephenson}}

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