Alien Trilogy doesn't support Glide (at least not my version). Just standard 256 and VESA modes. So there's no point in using GliDOS.

Very few DOS games supported Glide so it's not safe to assume that "since it was released in 1996" that it uses Glide.

Well, I know that it supports some Matrox and Diamond cards, so why not Glide? Weren't 3DFX cards the most popular 3D graphics cards back then?

Hello?

3dfx cards probably came later. Have you tried looking for a patch maybe?

There's a patch that adds on support for some cards, but not any 3DFX cards, so it either already supports 3DFX cards or doesn't at all.

http://www.mobygames.com/game/dos/alien-trilogy/techinfo

Looks to me like it didn't have any accelerator support out of the box - at least none that was advertised.

That site is wrong then. When you start up the game, it tries to dectect your video card.

This thread is annoying me.

From the Readme.txt

Video Cards ----------- […]
Show full quote

Video Cards
-----------

Incompatibilities

Unfortunately these video cards have conflicts with Alien Trilogy using
16 bit colors. You may need to install Alien Trilogy in 256 colors.
This will alleviate the conflicts.

MATROX 1280
MATROX 2000
DIAMOND SPEEDSTAR VGA ISA
DIAMOND VIPER PRO WEITEK 9100
DIAMOND STEALTH 64 GRAPHICS 2001 SERIES (ARK2000)

CIRRUS LOGIC CD-GL54x

On some portable and laptop PCs you may find that your video set up
will only run Alien trilogy in 256 colors.

-=-

Alien Trilogy tries to work out your computer configuration in order
to provide the best possible gameplay. On some rare occasions,
however, it may experience problems assessing your video set up
and may not initialize your card correctly. If you find this is the case,
type:

TRILOGY -nvd

and the program will run in default VESA video modes.

-=-

If you cannot get Alien Trilogy to work in high color mode, try
installing the game with 256 colors.

Check out our websites for any patches.

It looks to me like all it does is look to see if your video card is capable of 16bit graphics modes.

If you care to run INST.exe (the installation program) you will see a screen that shows:

486DX2 66mhz in 256 colorss
486DX2 66mhz in 16bit color
Pentium Processor in 256 colors
Pentium Processor in 16bit color

which likely just configures certain settings to make the game run properly on different hardware/video cards.

I DON'T SEE ANY MENTION OF 3DFX/GLIDE/VOODOO, etc.

The latest DateTime stamp on my Alien Trilogy files lists 11/7/96. (MobyGames lists a release date of Nov 30, 96 http://www.mobygames.com/game/alien-trilogy/release-info ) Since the Voodoo 1 wasn't released until October 96 (http://en.wikipedia.org/wiki/3Dfx) and 3DFX was a nobody to game companies at that time I highly doubt that there's a glide version of Alien Trilogy.

That's the readme.txt that comes with the patch, it's listing the cards that it adds support for, it doesn't mention what cards it already supports. And the time stamp on trilogy.exe in my version is December 31st, 1996. 1:43:40 AM. So it still could have Glide support.

uh, no that's from the README.TXT included with the game:

--= Alien(tm) Trilogy PC CDROM =-- […]
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--= Alien(tm) Trilogy PC CDROM =--

(C) 1996 Acclaim Entertainment, Inc.
Internet: http/www.acclaimnation.com

Developed by Probe Entertainment Ltd.
Internet: http//www.probe.co.uk

TM & (C) 1996 Twentieth Century Fox Film Corporation.
TM Designates a trademark of Twentieth Century Fox Film Corporation.

ALIEN, ALIENS, ALIEN 3,
TM and (C) 1979, 1986, 1992, 1996,
Twentieth Century Fox Film Corporation.
All rights reserved.

We have made every attempt to make Alien Trilogy compatible with as
many PC system configurations as possible. This file contains some
important information. It is important that you read this as there
may be some information critical to your PC configuration.

The information below may help you if you find that Alien Trilogy
does not run as you'd expect. Please check our websites for any
patches or updates to the game.

For additional options, type TRILOGY /? from DOS.

Default Controls
----------------

Gravis Grip
-----------
Directions : As you'd expect.
Shoulder buttons : Strafe left/right.
A : Fire 1.
B : Do/Use.
C : Charge/Grenade (Fire 2).
X : Run mode.
Y : Change weapon.
Z+Y : Look up.
Z+B : Look down.

VFX1 Headgear
-------------
Look left/right : Rotate left/right.
Look up/down : Look up/down.
Rotate cyberpuck f/w : Move forwards.
Rotate cyberpuck b/w : Move backwards.
Tilt cyberpuck left : Strafe left.
Tilt cyberpuck right : Strafe right.
Top fire button : Fire 1.
Middle fire button : Do/Use.
Bottom fire button : Fire charge/grenade (Fire 2)

Keyboard
--------

Keypad arrows : Directions as you'd expect.
Ctrl : Fire 1.
5 on keypad : Fire 2.
Space bar : Do/Use.
< : Strafe Left.
> : Strafe Right.
1-5 : Select weapon.
6 : Next weapon.
Backspace : Turnaround.
Caps lock : Run mode.
Shift : Run modifier.
Alt : Strafe Modifier.
Tab/ESC : Weapon select
PAUSE : Pause.

Mouse
-----
Left button : Fire 1.
Right button : Fire 2.

Directions : As you'd expect.

Spacetec 360
------------

Push Down (away) : Move forwards.
Push Up(towards) : Move backwards.
Rotate ball to left : Rotate left.
Rotate ball to right : Rotate right.
Rotate ball up : Look up.
Rotate ball down : Look down.
Translate left : Strafe left.
Translate right : Strafe right.
A : Fire 1.
B : Fire 2.
C : Change weapon.
D : Do use.
F : Fast (run) mode.

-=-

Windows 95 Users
----------------

To ensure that Alien Trilogy runs correctly on your particular set
up, we advise you to run WTRILOGY.EXE as this should help to make the
game run smoothly. You may find, however, that in some rare
occasions the movies do not play correctly.

-=-

Troubleshooting
---------------

Spacetec 360 users
------------------

You must run SPWTRIL.EXE to use the Spacetec 360 with Alien Trilogy.

-=-

VFX-1 Headgear
--------------

Please note that this hardware will only work in 256 color mode.

Ensure that you have properly calibrated your VFX-1 before playing
the game.

Memory
------

If you find that you are getting out of memory errors while running
Alien Trilogy or movies, try some of the following:

1) Before running Alien Trilogy type SET DOS4GVM=TRILOGY.VMC (See
below)
2) Install the program to run in 256 colours.
3) Boot from a clean floppy disk.
4) Remove memory resident programs.

-=-

TRILOGY.VMC
-----------

You may need to edit this to get Trilogy to work on your system. The
PhysMin is the amount of memory Trilogy requires. PhysMax is the
amount of memory FREE on your system. We suggest you increase PhysMax
until the program runs with the movies.

-=-

Video Cards
-----------

Incompatibilities

Unfortunately these video cards have conflicts with Alien Trilogy using
16 bit colors. You may need to install Alien Trilogy in 256 colors.
This will alleviate the conflicts.

MATROX 1280
MATROX 2000
DIAMOND SPEEDSTAR VGA ISA
DIAMOND VIPER PRO WEITEK 9100
DIAMOND STEALTH 64 GRAPHICS 2001 SERIES (ARK2000)

CIRRUS LOGIC CD-GL54x

On some portable and laptop PCs you may find that your video set up
will only run Alien trilogy in 256 colors.

-=-

Alien Trilogy tries to work out your computer configuration in order
to provide the best possible gameplay. On some rare occasions,
however, it may experience problems assessing your video set up
and may not initialize your card correctly. If you find this is the case,
type:

TRILOGY -nvd

and the program will run in default VESA video modes.

-=-

If you cannot get Alien Trilogy to work in high color mode, try
installing the game with 256 colors.

Check out our websites for any patches.

-=-

Installation Notes
------------------

During installation, a file called TRILOGY.BAT is placed in the root
of your C: drive (C:\TRILOGY.BAT). This file will not only execute
Alien Trilogy for you, but it is used by some programs to locate the game
on your system and indicate that a successful installation has taken
place.

Removing this file will not stop you from playing the game but may
make some peripheral programs believe that Alien Trilogy is not
installed.

-=-

In-game speech
--------------

The speech samples are only available if you have enough memory available.
If you do not, see MEMORY above.

-=-

We hope you enjoy the game.

....::::::The Alien Trilogy Team.

The patch just fixes these issue:

Fixes. ------ […]
Show full quote

Fixes.
------

This patch fixes many problems including incompatibilities with the
following video cards:

Matrox Mystique
Matrox Millenium
Cirrus Logic
Diamond SpeedStar
Diamond Viper
ARK 2000PV (including Diamond Stealth Graphics 2001)
64 megabyte install error

So far I've seen no mention of 3dfx anywhere in the readme's or on the box shots, which makes me think that it just uses VESA 640x480 or somesuch.