SCI: Sierra’s Next Step

By Adam Rodman

Evolve or die … it’s a sad fact of existence. Things that cannot adapt
to a changing environment slowly die out. So it has been for billions
of years. The same thing was happening to Sierra On-Line’s adventure game
interpreter, AGI, back in the late 1980s. It had spawned multiple versions,
created over a dozen games; still, the emerging PC age had rendered AGI
obsolete. And so Sierra On-Line developed a new interpreter … SCI.

SCI, an acronym for Sierra Creative Interpreter, made its debut in September
of 1988. Kings Quest 4, the last of the AGI games and one of the
first SCI, was created in two versions–one in SCI, the other in AGI.
Through the years, SCI spanned three unique versions and authored more
games than AGI and possibly more than any other engine (though that is
doubtful) …

SCI is an interpreter (hence the “I” in the acronym.) The actual
interpreter is, essentially, a virtual memory. It compiles program code
into a game or program. SCI relies on object-oriented programming. This
makes it easy to change basic behavior of graphics, backdrops, and sounds.
Says Lars Skovlund of the FreeSCI project, “For instance, the game
designer may want a computer-controlled actor to walk casually along the
street or chase the user character. Both things are accomplished with
the same ease.”

Program code is similar to Objective C. An example, kindly given by Lars
Skovland:

(instance ego of Actor
     (properties
          view 4
          loop 1
          cel 0
          x 230
          y 115
     )
)

This code shows where the ego (or player character) is located and what
it looks like.

Like everything,
SCI has evolved over the years. The first version was entitled SCI0. The
original SCI interpreter, it was used from 1988 to 1990. It was light-years
beyond AGI’s graphical system, sporting high-res 640 x 200 and
16-color graphics. All of the graphics were vector-based, not pixel-by-pixel.
Music was FM MIDI (i.e., Adlib, Sound Blaster.) The games themselves were
controlled by a combination of mouse and keyboard. A mouse-click would
have the player character walk, and a parser was used to control all other
commands (though the keyboard could be used for walking also). Space
Quest 3, Kings Quest 4, and Leisure Suit Larry 2 and 3 are
just some of the games programmed in SCI0.

The next version of SCI was appropriately titled SCI1, and it was launched
in November 1990 with Kings Quest 5. The graphics were changed
to low-resolution 256-color and were hand-drawn. Digital sound effects
were added, though music was still MIDI. Undoubtedly, the largest difference
between SCI1 and its forefathers was the scrapping of the parser system
for a new point-and-click system. Much like LucasArts’ SCUMM system, commands
were added like walk, use, talk, look, and inventory. Though the games
released with SCI1 were far more user-friendly, many hardcore adventure
purists hated the new point-and-click system. Space Quest 5, Kings
Quest 5 and 6, and Leisure Suit Larry 5 are just some
of the games to use SCI1.

The third and final version of SCI was SCI32. Launched in 1994, SCI32
threw in a very important feature to the SCI mix–32 bits. Until this
time, the Sierra SCI interpreters were all in 16 bits, which caused quite
large memory restraints (restraining what programmers could do.) FMV and
high-res graphics were the most obvious updates to the SCI interpreter.
Space Quest 6, Kings Quest 7, and Torin’s Passage all used
SCI32.

However, in 1997, Sierra On-Line apparently stopped using SCI (or at
least used a heavily modified version of it.) And thus ends the legacy
of the Sierra adventure interpreters …

Now stop crying and remember to tune in next week when LucasArts’ very
SCUMM-y system is put in the spotlight.

Thanks to Lars Skovlund and Joakim Moller for their
interviews.