Portal: Prelude, as its name states it, is an unofficial prequel to the game Portal. Its story revolves around the pre-GlaDOS epoch, even before she was plugged in. At this time, test subjects were monitored by real Aperture Science employees, whose work was tedious, lengthy and repetitive. This is why they decided to build a great artificial intelligence that could both replace them in these difficult tasks, and also take responsibility for many other tasks within the complex and compete with Black Mesa's superiority. All employees of the Aperture Science complex are now eagerly awaiting GlaDOS. Maybe even a little too eagerly, as the upcoming events will tell... This game is totally free. It offers a bit more gameplay hours than the original Portal, with 8 chapters, 19 test chambers, 48 challenges, 6 advanced maps, a brand new storyline and more than 400 lines of english speech with dozens of subtitles translations.

Upload a file Report abuse Portal: Prelude 1.1.5 (complete installer)
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Feb 2nd, 2009
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This new version is shipped with more than 115 bug fixes, improvements and additions (since 1.0.0). We know everything's still not perfect, but we believe we put enough work in this mod and thus, this version should be considered final (except if something really bad happens). Please note because of steampipe there is a simple fix that you need to make to gameinfo.txt which is the same for every portal mod.

Extract to sourcemods folder. Open gameinfo.txt inside the Portalprelude folder. Underneath Filesystem there should be a section called FileSystem:

replace it with this:

		SteamAppId				400
			game+mod			|gameinfo_path|.
			platform			|gameinfo_path|.

			// We search VPK files before ordinary folders, because most files will be found in
			// VPK and we can avoid making thousands of file system calls to attempt to open files
			// in folders where they don't exist.  (Searching a VPK is much faster than making an operating
			// system call.)
			game_lv				portal/portal_lv.vpk
			game+mod			portal/portal_english.vpk
			game+mod			portal/portal_pak.vpk
			game				|all_source_engine_paths|hl2/hl2_textures.vpk
			game				|all_source_engine_paths|hl2/hl2_sound_vo_english.vpk
			game				|all_source_engine_paths|hl2/hl2_sound_misc.vpk
			game				|all_source_engine_paths|hl2/hl2_misc.vpk
			platform			|all_source_engine_paths|platform/platform_misc.vpk

			// Now search loose files.  We'll set the directory containing the gameinfo.txt file
			// as the first "mod" search path (after any user customizations).  This is also the one
			// that's used when writing to the "mod" path.
			mod+mod_write+default_write_path	|gameinfo_path|.

			// Add the mod directory as a game search path.  This is also where where writes
			// to the "game" path go.
			game+game_write			|gameinfo_path|.

			// Where the game's binaries are
			gamebin				portal/bin

			// Last, mount in shared Portal loose files
			game				|all_source_engine_paths|portal

			// Last, mount in shared HL2 loose files
			game				|all_source_engine_paths|hl2
			platform			|all_source_engine_paths|platform


Portal: Prelude 1.1.5 (released 2009-01-29)

* Added: german translation (subtitles only)
* Added: czech translation (subtitles only)
* Added: chinese translation (subtitles only)
* Added: unofficial slovak translation (see portalprelude.com)
* Fixed: italian subtitles corrupted by additionnal quotes (thanks to Matteo Piazza)
* Fixed: russian subtitles corrupted by additionnal quotes (thanks to Matteo Piazza)
* Fixed: korean subtitles corrupted by missing tag (thanks to Nevets_Look)
* Fixed: portuguese subtitles corrupted by missing tag (thanks to Nevets_Look)
* Fixed: typos in spanish subtitles (thanks to Siegfried Anderson)
* Fixed: test chamber 6 not reloading when failing
* Fixed: difficulties to fire portals through some of the white holes
* Fixed: ability to go back when reaching the end of chamber 12
* Fixed: time challenge for chamber 15 was a step challenge
* Fixed: in a rare case glados was still attacking when shutted down
* Fixed: ability to go under the elevator before it came back in chamber 18
* Fixed: flying ghost chair in aperture laboratories
* Fixed: random crashes should disappear, let's hope some others won't appear
* Fixed: glados laser starting too fast, increased the delay
* Fixed: a few soundscape problems
* Fixed: credited the correct people for the correct stuff
* Fixed: missing projector model textures
* Fixed: music played during the second boss-fight not playing correctly or not at all
* Fixed: several cubemap (reflections) visual glitches
* Fixed: ability to open the door to the three ballcatchers in level 19, by only using a cube
* Fixed: lighting artifacts in the last levels
* Fixed: GlaDOS randomly stops attacking in the second round
* Fixed: subtitles activated by default when the mod is launched for the first time
* Fixed: hundreds of trivial glitches and tiny stuff everywhere in the levels
* Added: new aperture science laboratories logos
* Added: simpler and clearer signage in the first levels
* Added: maybe one, two or three new easter-eggs?
* Added: the correct graph and soundcache files
* Added: new lighting effects near metal grates
* Added: new intro sequence (vault lift)

Portal: Prelude 1.1.0 (released 2008-10-29)

* Added: dutch translation (subtitles only)
* Added: finnish translation (subtitles only)
* Added: hungarian translation (subtitles only)
* Added: italian translation (subtitles only)
* Added: korean translation (subtitles only)
* Added: portuguese translation (subtitles only)
* Added: russian translation (subtitles only)
* Added: spanish translation (subtitles only)
* Fixed: portals not fizzled when you handed back your portalgun
* Fixed: installer problems (mostly with Windows Vista)
* Fixed: huge freezes and lags when GlaDOS is started
* Fixed: morality core going through a grate in the last level
* Added: a toggle mode to the BTS button in test chamber 19
* Fixed: camera won't fall in test chamber 15
* Fixed: ability to go inside observation rooms using an engine glitch
* Fixed: finishing test chamber 6 could lead to Mike saying you failed
* Fixed: Erik saying "euros" instead of "dollars"
* Fixed: ability to go inside the box dispensers using an engine glitch
* Fixed: advanced chambers/challenges still locked when finishing the game
* Fixed: autosaves not correctly activated
* Added: autosaves on challenge start
* Added: autosaves after long speeches
* Fixed: player could get stuck under elevators
* Fixed: challenge 15 won't record scores
* Fixed: challenge 17 won't record scores
* Fixed: box dispensers can drop more than one cube
* Fixed: typos in french subtitles
* Fixed: typos in english subtitles
* Fixed: portal fizzler in test chamber 17 gives a cube for a camera
* Fixed: missing faces resulting in visible outside of the level
* Fixed: non-solid door in test chamber 3
* Fixed: non-solid door in test chamber 4
* Fixed: cubes can get blocked in the dispensers tube
* Added: an escape path in test chamber 9
* Fixed: glass panel can be broken with a chair in the aperture laboratories
* Fixed: cube can be lost in the orbs room in test chamber 19
* Fixed: cube can be lost before the pit in test chamber 19
* Added: a cube dispenser in test chamber 14
* Added: an alternative path in test chamber 15 (for the challenges)
* Added: a delay when turrets appear in test chamber 8
* Fixed: bogus elevator in test chamber 10
* Added: a distraction in the turrets room in test chamber 11
* Fixed: radio song does not stop when the radio is destoyed
* Fixed: moving a few autosaves and areaportals to prevent the game from crashing
* Fixed: improving lipsyncing but it's still random as faceposer keeps corrupting our sounds
* Fixed: ballcatchers can be activated with any thrown object
* Fixed: scorpions' song replaced by four variations of still alive
* Fixed: door won't open in the corridor at the beginning of test chamber 18
* Added: hints at the end of test chamber 18
* Added: a disclaimer when the game starts
* Added: a ledge for the first jump in test chamber 2
* Fixed: turrets fire too quickly in test chamber 1
* Added: a ledge for the fling in test chamber 3
* Fixed: lunch bag model sounds like metal
* Added: english part to the commentary, to point out that there's subtitles
* Added: new "directional sign" textures for test chamber 19 BTS area
* Added: hints under the stairs in test chamber 19
* Added: another path to get to the BTS area in test chamber 19
* Fixed: particles and light color of disintegrators
* Fixed: particles color of "only-portals" fizzlers
* Fixed: rework a few textures for the BTS/maintenance areas to look less old
* Fixed: clean and optimize level geometry
* Added: missing challenge records for test chamber 15
* Added: missing challenge records for test chamber 18
* Added: missing challenge records for test chamber 19
* Fixed: GlaDOS force field insta-kills too randomly and too often
* Fixed: bogus NPC animations
* Removed: alternative solution for test chamber 4
* Added: space between "only-portal" fizzlers and disintegrators in test chamber 15
* Fixed: snoozing man is not snoozing
* Added: NPCs in some empty observation rooms
* Fixed: fizzler in test chamber 15 is destroying the energy orb
* Fixed: too many letal turrets in test chamber 15
* Added: hints in the 4-turrets room in test chamber 17
* Added: a glass panel to see the rotating wall in test chamber 17
* Added: missing tubes in box dispensers
* Added: crosses on wedge shaped platforms in test chamber 19
* Fixed: GlaDOS stops attacking after her second attack in the second round
* Added: restored stairs in the BTS/maintenance area in test chamber 15
* Added: clipping in most of the stairs to avoid view shaking
* Fixed: in a rare case, the cube isn't respawned in test chamber 17
* Fixed: in a rare case, the cube isn't respawned in test chamber 18
* Fixed: overlapping blocks in test chamber 19
* Fixed: at the end, the new menu doesn't show up if the console if visible

Portal: Prelude 1.0.0 (released 2008-10-10)

* Initial release

Preview Image
Portal: Prelude 1.1.5 (complete installer)
Post comment Comments  (0 - 50 of 102)
Tron619 Feb 2 2009, 8:07pm says:

ZOMG thanks

+4 votes     reply to comment
InStars Feb 3 2009, 3:45pm replied:

i wish i had a carrot to eat...

+17 votes     reply to comment
Crypt May 17 2010, 11:00pm replied:

I wish I had a black forrest cake to eat...

+11 votes     reply to comment
Marvin.Damstra Sep 30 2010, 4:17pm replied:

you can't have it, it's a lie

+6 votes     reply to comment
K00PD4WG Dec 6 2010, 4:57pm replied:

good thing the cheesecake isnt :D

+4 votes     reply to comment
blackopsmaster Jan 2 2012, 6:22pm replied:

lol hmmm maybe there a choclate pie thats not a lie

+1 vote     reply to comment
Guest Jan 2 2014, 3:11pm replied:

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Ballads Mar 7 2009, 10:34am buried:


it doesnt work!

-21 votes     reply to comment
NuBiTo Nov 22 2009, 11:41am replied:

lol why is it burried? wat so bad about eating carrot. He's just being random. thats all

+16 votes     reply to comment
NeRvE_Relapse Oct 15 2010, 2:02am replied:

Because Of Too Many Negeative Votes lol

+4 votes     reply to comment
Chocolate-Helicopter Oct 12 2013, 12:49pm replied:

this comment is old

+1 vote     reply to comment
UACmarine208 Feb 3 2009, 11:26pm says:

i hope this was before the cake was a lie XP

+3 votes     reply to comment
Colossal Feb 4 2009, 9:51pm replied:

It is before the lying cake.

+4 votes     reply to comment
ZedoMann Feb 12 2009, 9:13am replied:

There was no such time...

-3 votes     reply to comment
Davkilla101 Apr 8 2009, 11:05am replied:

Actually there was i played through it and there was cake :P

+14 votes     reply to comment
doctorwhoy1 Jul 14 2009, 1:31pm replied:

There was a cake but GlaDos wasnt gonna give it 2 u,,
The cake wasnt a lie, but the escapees though so..

+9 votes     reply to comment
The_Error May 13 2010, 6:18am replied:

Noooo. The cake was a lie, because GLaDOS said that everyone will get cake, but what they got, was death.

+2 votes     reply to comment
sage321 Apr 14 2012, 7:17pm replied:

dude the cake is not a lie. its called no-clip.

+3 votes     reply to comment
KEVLAR60442 Jun 27 2010, 10:52pm replied:

The previous test subjects got baked, and then there was cake. in addition to dirt and swedish fish, the cake has Cave Johnson in it.

+1 vote     reply to comment
overlordluke Jan 30 2012, 12:09pm replied:

no when glaDos says you will be baken and then there will be cake there is a platform going into the fire she just hinting because she says she can't lie to you

-1 votes     reply to comment
Marvin.Damstra Sep 30 2010, 4:20pm replied:

can't be, it's a lie

+1 vote     reply to comment
D3VIL Feb 7 2009, 1:54pm says:


+4 votes     reply to comment
CyberAltair Feb 19 2009, 12:27am says:

Damn, I really wanted to play this but with my internet connection this will take a lot of time =\

Isn't their as possibility of putting it in a .rar file in the future?

+4 votes     reply to comment
matthijs186 Oct 7 2010, 5:43am replied:

They did, check it out!

+1 vote     reply to comment
Colossal Feb 20 2009, 9:10pm says:

No ModDB mirror?

+9 votes     reply to comment
ContentRobby Feb 24 2009, 3:07pm says:

how do you find the file to play it I downloaded it for like 1 hour now i cant find where to play it please help mod db.

-1 votes     reply to comment
sudoku424 Mar 2 2009, 6:17pm replied:

First, you must go to where you downloaded it to and then use that to install the game. Then, Steam must be restarted(or just started, if it wasn't running when you installed Portal Prelude), and then it will be in the games list of Steam.

+1 vote     reply to comment
pie32 Jan 30 2010, 12:28pm replied:

put the download under steam/steamapps/sourcemods then it will be in your steam game list as a third party mod :D

+1 vote     reply to comment
matthijs186 Oct 7 2010, 5:29am replied:

that's right, a third party mod!!

+1 vote     reply to comment
usbpetrock Feb 4 2012, 11:19pm replied:

It's an executable. You run it.

+1 vote     reply to comment
LopperUK Mar 5 2009, 1:08pm says:

it must of took a long time to upload a file THAT big XD

+2 votes     reply to comment
Ballads Mar 7 2009, 10:54am says:

sorry false alarm :"

+1 vote     reply to comment
randosity42 Apr 11 2009, 11:18pm says:

installer at 1 percent...lol

+2 votes     reply to comment
Killer_man_1996 Apr 23 2009, 3:03pm replied:

ME TOO... :(

+2 votes     reply to comment
SkyJack3R Jun 29 2009, 1:18pm says:

This Prelude version looks good :o)
I'm gonna check this out ^^

+2 votes     reply to comment
maxpayne05 Jul 15 2009, 5:05pm says:

hi guys is there out a tutorial to install this ?


0 votes     reply to comment
Davkilla101 Jul 16 2009, 4:20pm replied:

Uh the file is actually an installation wizard so just follow the steps that it asks for.

+2 votes     reply to comment
matthijs186 Oct 7 2010, 5:42am replied:

And you must put the files in the map ''sourcemods''

+1 vote     reply to comment
Devian50 Dec 12 2010, 5:01pm replied:

uhh you mean folder? lol

+1 vote     reply to comment
AmaroqDricaldari Apr 2 2011, 10:44pm replied:

Will it replace my Portal Files if I use the installer? Or am I safe if I don't back up the Portal Files?

+1 vote     reply to comment
Schinchan56798 Sep 18 2011, 4:04pm replied:

No, just install into the folder sourcemods, Restart Steam, and there you go the mod should be in your games library on steam.

+1 vote     reply to comment
Guest May 20 2014, 6:28pm replied:

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Croco15 Jul 17 2009, 1:45pm says:


+3 votes     reply to comment
GhettoGarden1 Jul 28 2009, 7:30pm says:

mmm carrots

+1 vote     reply to comment
Persnoody Aug 18 2009, 10:32pm says:

Hmmm >downloaded >installed but for some reason steam doesn't recognize this as a game. Anyone got any ideas? I really want to play this game.

+1 vote     reply to comment
NuBiTo Nov 22 2009, 11:42am replied:

are you sure you place it in the right folder? Do you have the orange box?

+1 vote     reply to comment
Alsnana Aug 26 2009, 12:43am says:

Cool mod and i like it ^^

+1 vote     reply to comment
Suranyi Aug 29 2009, 9:56am says:

800mb, wtfbbqhax!! xD
Maybe dl this when I'm sleeping.

+1 vote     reply to comment
zck2020 Nov 28 2009, 1:18pm says:

This mod is excellent, only thing I would change is the voice acting. Other than that it was fun as hell to play!

+1 vote     reply to comment
REENIGAV Dec 6 2009, 7:42pm says:

this mod is awesome!! thanks to upload!

+2 votes     reply to comment
Guest Jun 10 2013, 5:44pm replied:

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Released Oct 2008
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