Some extra info about Sierra’s game engines…

AGI was indeed first used in KQ1, though earlier Sierra adventure games (even going back to Mystery House in 1980) used something extremely similar. AGI was just formalizing what they’d done before and setting it as a common platform for all future games.

In those days, it was, of course, not possible to write an entire adventure game in machine code because there wasn’t even memory to hold more than a handful of screens. The use of bytecode was as much a compression scheme as anything else. So AGI was just a bytecode interpreter. Vector graphics primitives (e.g., draw line, flood fill) could be written in just a few bytes, much better than machine code.

Ken Williams made a splash with early Sierra games because he had an extremely simple insight that most others at the time didn’t seem to have: for graphics operations, allow points to be on even-numbered x coordinates only. Most platforms had a horizontal resolution of 320, too much for 1 byte. Ken Williams had his early game engines divide every x coordinate by 2 so that it could fit into a single bit (essentially getting only 160 horizontal pixels). A silly trick, but it got big memory savings, and allowed him to pack more graphics into RAM than many other people could at the time.

After AGI (KQ3 was the last King’s Quest to use AGI), Sierra switched over to their new game engine/bytecode interpreter: SCI. SCI was rolled out in two stages, though.

SCI0 (e.g., KQ4) was 16 colours and still revolved around the text parser. SCI1 (e.g., KQ5) was 256 colours and was point-and-click. (SCI2 and later were full multimedia)

For the game player, the major differences you’ll notice between AGI and SCI0 (both 16 colours, both text-based) are that SCI0 renders using dithering, gets full horizontal precision (x coordinates stored in 2 bytes), multiple fonts, support for real sound devices (MT32, Adlib). For the programmer, though, AGI and SCI0 were pretty radically different. SCI0 as a programming language was an object-oriented vaguely Scheme-inspired sort of language, and was actually pretty radically different from AGI.

I grew up on this. Taught me both how to handle a computer and English. Fond memories.

That was the first computer game I was ever gifted, and the copy protection made it not want to boot on our Apple IIe.

So I’d leave it trying to boot and after a half hour or so it’d load.

There were multiple solutions to every problem and a completely nonviolent ending.

On one screen you’d have to hide behind a tree and wait a few minutes for the giant or ogre to fall asleep so you could take what he had or sneak past. If course the only alternative there was violence.

There were also totally obvious puzzles as the screen drew slowly enough for you to see the hole before the rock you could move was drawn ontop of it.

Here is an alternative Piped link(s):

Space Quest Historian - King’s Quest: A Fair and Balanced Retrospective

Power Pak - King’s Quest - The First Adventure

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