[2] King's Quest caused a sensation in the burgeoning market of PC-compatible computers, and Sierra sold more than half a million copies.
Since the SCI engine required a more powerful home computer, Sierra released an AGI version of the game at the same time.
The following year, Sierra published its final AGI-based title, Manhunter 2: San Francisco, then focused exclusively on SCI for new adventure game development.
Among SCI's enhancements were a more versatile scripting system, an object-oriented programming model, higher-resolution graphics (320×200 rather than 160×200), a point-and-click interface, and support for additional sound card hardware.
The technical complexity of King's Quest made it a burden to write in assembly language, so the programmers created a game engine to simplify development.
[1] Beginning with AGI version 2, the game engine drew graphics in an off-screen data buffer, then blitted them into video memory.
These included the IBM PC compatible, the Atari ST, Commodore's Amiga series, and Apple's Macintosh computers.