First brought to my attention by Destructoid on Sunday, it seems Valve and some indie devs have been having some fun... with unknown as of yet implications. Strange glyphs and texts have been popping up all over the place in the games found in 'The Potato Sack' pack, and of course the internet has been all over it. Here's a link to the Valve ARG wiki, and I'll be updating this OP with findings, big or small.
Well, what say you? It seems a bit elaborate for a one day April fools thing :O
April 9, 2011
12:40: Unlock.png Various concept art (pictured) has been discovered within archives included in the DLC given for successfully logging into the Aperture Science login page. Changing the alpha channel on this concept art seems to give cryptic photographs, all taken in and around Seattle. Concept art is here: http://imgur.com/a/IdNDV#Px8rt
12:20: Unlock.png All newly updated games contain archive files with alpha-numerical names. Check IRC and Aperture Science login page for further details as they come in.
12:17: Unlock.png Login for Cogs Aperture Science login page is "movable panels", taken from the Toki Tori psuedo-glyph solution. Logging in here grants you a potato and again, an update to the game.
12:16: Unlock.png Login for The Wonderful End of the World Aperture Science login page is found to be "every piece". This is from the Cogs glyph puzzle solution. Logging in here grants you another potato and it also updates.
12:11: Unlock.png Login for Killing Floor Aperture Science login page is "failed experiments", taken from Audiosurf. Logging in here grants you a potato and again, an update containing more DLC.
12:01: Unlock.png Login for Audiosurf Aperture Science login page is "rail rider", taken from the RUSH level code. Logging in here grants you another potato and more DLC.
11:54: Unlock.png Login for AaAaAA!!! Aperture Science login page is discovered to be "long fall", taken from a BIT.TRIP.BEAT achievement. Upon entering this successfully, a login screen appears, the game updates with the DLC, and adds a potato icon to the users Steam profile. (Example).
10:13: Email icon.png IRC user "Aaron" recieves a new e-mail containing another small image. It shows a two-player game of Carcassonne, using the River 2 extension. "Athenor" also receives an e-mail, as does DireThoughts.
10:06: Globe.png The Bathysphere has been found to have nothing immediately relevant to the ARG in or around it. Focus should probably be re-aimed at other parts of the puzzle, and the new email(s).
09:45: Twitter-Icon.png @RayTheSun tweets, seemingly related to Team Meat's last message.
09:39: Globe.png IRC user dotreptile's brother visited the Bathysphere location. It was on display outside the shop. Photos here.
09:27: Unlock.png The third RAR (003.rar) in Amnesia is unlocked, using the password "Tin Hinan". It contains two files: a drawn image (enhanced image) & a PDF-file which contains some text and this string.
09:17: Globe.png IRC user dotreptile has informed that his brother will visit the Bathysphere location and report any findings.
07:41: Potato.png The login page for RUSH was found but no method was given. It is assumed it was acquired using the game files and not in-game methods. Keep discussion on #ValveARG2-RUSH.
07:40: Globe.png IRC user Flamov finds this real life Bathysphere by searching on Flickr, original source here. It's real-world location has been determined to be here.
06:30: Unlock.png The second rar-file (002.rar) in Amnesia is unlocked, using the password "cruel love" (received by decoding the numbers in 001_.jpg). It contains two files: an image of woman, a letter to Madeleine in PDF-format. The italic letters in the PDF-file write the text "FRIENDSLEGEND". These can form "DEFENSE GRID" but that leaves an 'N' and the 'L'. The image-file contains 12 hidden letters which results in "THE FOREIGNER".
05:00: Unlock.png The Toki Tori pseudocode puzzle is solved and yields the pattern "MOVABLE PANELS".
03:00: Unlock.png The first of four rar-files (001.rar) in Amnesia has been extracted. The password is "TCHUMHULYTSHO". It contains two image files: 001.jpg contains a hidden code of 13 letters, 001_.jpg is an abstract talking about a certain castle Brennenburg in Germany.
02:31: Unlock.png Amnesia's CTHULHU MYTHOS and the connection to Harold and the Gods.
02:04: Email icon.png Jake receives another mail from the mysterious everythingis finehere. It mentions "matrimonial urges". Most likely this has something to do with the CamelCaseWedding music file he was sent.
01:05: Twitter-Icon.png Hubert Uberson tweets again. Sandy writes a new blogpost which she deleted again and replaced with another blogpost.
00:35: Email icon.png Email recieved from everythingis finehere by NovaSilisko. Refers to 'the pole climber' aka Jake_R, the person who visited Two Tribe's offices, or alternatively the Vimeo account that uploaded the surveillance video of Jake_R. Various other people got a mail as well, now with an image attached. If you get an e-mail, please update that page or ask someone in IRC to do it.
April 8, 2011
22:30: Unlock.png Killing Floor's Alien 8 hint has been solved, points to 'man-o-lantern' model.
22:00: Unlock.png A recruitment drive has been found in Defence Grid. It would appear that players are given a random ID, and need to signup within the console. We need people who meet the current signup requirements to signup and answer the question correctly. Join #ValveARG2-DG if you meet the current requirement. Instructions here (in short: fill out THIS).
21:15: Unlock.png Omen is cracked!
20:41: Unlock.png Amnesia's Unexpected Omen nearing crack!
20:04: Globe.png Valve updates the Portal 2 steampage with link to the Portal 2 comic on Portal's official website: http://www.thinkwithportals.com/comic/ (the images are now also available without text and bubbles)
20:04: Twitter-Icon.png Team Meat tweets again referring to potatos: "no one seems to follow the ray of sun to the potato patch..." More information here.
19:10: Unlock.png The mosaic/lego puzzle in Defense Grid is finally solved. It spells out the message: NOCAKE This was used in the DG console to unlock a hex dump, leading to a password for jsharman's folder, which held a dot game. When won, this opened the Aperture Science Login Page for Defense Grid.
17:42: Unlock.png The decoding of the bathysphere has finished! See Emails from Gabe Newell for the finished translation. It evidently refers to 1... 2... 3... KICK IT!. There are numbers and symbols in between the letters of the translation, that together form "4/19/2011 7AM = 4/15/2011 9AM". This could be the date when Portal 2 is available for "pre-download" on Steam. However, "4/19/2011 7AM" is when Portal 2 unlocks on Steam.
17:00: Unlock.png The real last image of the bathysphere puzzle has been found (check this tweet). It was sent to Kotaku but in true fashion they didn't get around to posting it (proof). The old image (on the left here) was a confirmed troll.
15:03: Twitter-Icon.png Jeff Pobst states on twitter that they're "willing to help out with defense grid", probably referring to the mosaics puzzle. They then link this image and inform people to go to their office in Bellevue, Washington, before 6:00 PM and enter the door shown in the picture to get help with the puzzle. Users sporge  and nexizen  successfully arrive, as reported by followup Twitter messages from Pobst.
14:30: Twitter-Icon.png @SuperMeatBoy tweeted an image of a dead bird (and shortly after another bird). This has been taken to mean that we should stop looking on Twitter for clues. 20 minutes later they tweeted "these birds aren't red they are yellow".
13:00: Potato.png The secret level in The Wonderful End of the World has been reached! File:Cave.mp3 is playing in the level and appears the same song that is playing in Hubert's video, with lyrics. Please go to #valveargmp3 to help compile the lyrics.
12:20: Globe.png Part 1 of the Portal 2 comic was posted by IGN. Does not appear to have any additional clues to the ARG. (The binary code on one page translates to "The cake is a lie".
12:19: Potato.png An update was applied to Amnesia. Please join #valvearg2-AMNESIA to discuss. And check Frictional's forum; there's a fiction going on that has yet to be explored.
11:10: Globe.png A Google account is discovered. After piecing together the conversation, we find that it leads to the colored version of the secret level on Wonderful End of the World (referred to in the e-mail that was sent to MiKaXuS.) Holding down while starting the Arcadia level gets you into the colored secret level, and scoring an "A+" on the level in timed mode unlocks the Aperture Science login screen.
10:40: Unlock.png Defense Grid Flower_Alchemy puzzle is solved by Ninjai. The password to flower_answer.txt is "theyrealldaisiestome". On login screen this leads to the name "jsharman", which points to a TinyURL and the discovery of the final piece of the Bathysphere puzzle.
10:30: Email icon.png An email received by chrisrandazzo was given to Aaron on the IRC network containing a series of numbers, each line being a palindrome.
10:21: Potato.png A new message appears in Killing Floor. Clearly, Tripwire feels unappreciated.
10:06: Blogger-logo.JPG Sandy May Or May Not be Fictional blog has been updated. It reads that she has something in her spam folder, and she talks about the warehouse, like Hubert. (There was a conversation between Hube and Rube last night)
09:25: Unlock.png "Comments" in the MP3 file Searching, Emergence, Discovery reads as 123123123123123123123123123123123123123. When played in 1... 2... 3... KICK IT! a percentage is shown at the bottom of the screen. When one obtains 50,000 points or above (and in doing so gets 100%), an Aperture Science login page appears.
09:23: Email icon.png IRC user MiKaXsUs receives an e-mail from the same address as Jake_R.
08:56: Unlock.png Inside the Razer file (SED.zip) an MP3 file is discovered, called Searching, Emergence, Discovery. Also available on Youtube. Efforts are at work to decode the meaning of the song and find out what the information presented there is used for. Please join #valveargmp3 to discuss.
08:28: Unlock.png Email icon.png Jake_R receives an OGG audio file from a user named everythingisfinehere (return email: firstname.lastname@example.org). Spectrogram shows "WhyMustThereBeSiblingRivalry" which is the password of Razer's SED.zip.
07:11: Unlock.png A Razer link is discovered to a ZIP file with an MP3 inside, reached by decoding the paper flower.
07:03: Potato.png The method to enter the Wonderful End of the World secret level was found: hold [Shift]+ while entering Word Forge (including the loading screen).
06:23: Unlock.png The paper flower is solved by LazarusGrey.
06:00: Potato.png A secret level was found inside The Wonderful End of the World, but it is unclear exactly how to reach it.
02:25: Globe.png New image revealed by Rock Paper Shotgun. Leaving one remaining image to find.
April 7, 2011:
23:17: Unlock.png Images from Toki Tori's zip file have modified thumbnails embedded in the EXIF. These contain pseudocode 1, 2, 3.
23:07: Twitter-Icon.png New tweets from Rube Uberson  and Hubert Uberson . (Tweets formatted into a conversation for clue searching .)
23:03: Unlock.png The patterns from Toki Tori's map were transformed into a QR code and a zip file with 3 images inside.
21:34: Twitter-Icon.png A new piece of the image has been sent to Phillip Ryu over Twitter.
21:17: Email icon.png Electronista report a new image from Gabe Newell.
20:45: Potato.png There are new sounds playing in The Ball when certain criteria are met.
20:29: Email icon.png Attack of the Fanboy report another image titled "sort eco probes". This appears to be the same as the image received by Joystiq.
20:29: Unlock.png The Gabe Newell image filenames are all anagrams of "REBOOT PROCESS".
20:24: Unlock.png The Facepunch thread confirmed that the images go together.
20:16: Email icon.png MacRumors reports that they received this image, again similar but different from the previous ones. The image is titled "sorbet coopers.jpg".
20:04: Twitter-Icon.png Macworld Editing Associate and One FPS blogger David Chartier reported via twitter that he received another image similar, but again different from, the previous two from Joystiq and HecticGlenn. The image is titled "bee torso crops.jpg" according to MacRumors. This image appears to fit together with the image received by Joystiq, suggesting these images are puzzle pieces and the numbers may be another code.
19:39: Unlock.png The Audiosurf Aperture Science login page is discovered after beating the song Icy_Murderous_I.mp3 on Ninja Mono, hitting all coloured blocks and no greys.
19:35: Email icon.png ARG player and lead editor of halflife2.net, HecticGlenn, receives an email from Gabe Newell containing an image titled "berrets or scoop". The image contains some 20-odd numbers. Joystiq also reports receiving a similar, but different image.
19:20: Unlock.png The Cogs Aperture Science login page is found.
19:06: Unlock.png The Toki Tori Aperture Science login page is found.
18:45: Twitter-Icon.png Hubert Uberson tweets more, this time adding two photos 1, 2. One of which shows codes in the shape of a flower, most likely referring to the flower page found in Defense Grid.
18:26: Unlock.png It seems the Aperture Science login pages require the user to be logged into their account on steamcommunity.com and checks if they've met the conditions that way too. This means that only the people who gain access to the page can try potential passwords.
17:50: Potato.png A new item is introduced to Team Fortress 2, the Resurrection Associate Pin, and a mysterious Potato badge (POrTAl TwO) appears on the profiles of those that receive it.
17:42: Unlock.png Glyphs are found on the side of the truck in the Toki Tori Surveillance video, which when matched with their letters gives "FLIP UNTIL THE DOTS MATCH"
17:39: Unlock.png It is found that buying the potato item in Killing Floor shows the Aperture Science login page.
17:31: Unlock.png RUSH has codes on the underside of all levels. See the screenshots here and the codes here.
17:30: Twitter-Icon.png The moment the Wiki goes live, Hubert Uberson tweets once more: "I found the most interesting thing in my Spam folder today."
17:21: Unlock.png Dying in Super Meat Boy Level 19 on chapter 4 (Hell) a few times will bring up an Aperture Science login page.
14:26: Youtube logo.gif As part of the Defense Grid update, a video is linked to which reveals that Jake_R was filmed from across the street when he discovered the Toki Tori Glyph.
14:20: Potato.png All Potato Sack games received an update, which removes potatos from most of the games. More information on the Valve news pages.
14:00: Unlock.png Killing Floor achievement descriptions decoded, revealing 5 glyph/letter combinations and the hint: "sixteen and four is the way"
12:10: Potato.png New BIT.TRIP BEAT achievement added which relate to the ARG.
11:35: Potato.png New Killing Floor achievements added which relate to the ARG.
03:18: Blogger-logo.JPG Sandy's blog is back up with a new post a day after it was wiped clean.
03:00: Globe.png The Aperture Science login page has been taken down and replaced by an image of potatoes.
02:00: Unlock.png Completing the Cogs beta puzzle leads to a Aperture Science login page.
April 6, 2011:
23:00: Twitter-Icon.png The Super Meat Boy tweet the code "7fa6ce99d281". When asked if it has a relation to the ARG, they replied "I'm just glad it got into the right hands".
16:00: Globe.png IGN posts a preview of a new Portal 2 comic. They will post part one of the comic this Friday.
14:20: Potato.png All relevant games have been updated.
14:20: Potato.png Cogs beta update features a slider puzzle which includes 10 of the found glyphs.
10:20: Twitter-Icon.png The numbers in the Twitter code translate to "These are just numbers. If you like them so much, why don't you marry them?".
10:03: Twitter-Icon.png Hubert's twitter updates with several new codes.
09:54: Twitter-Icon.png Hubert's twitter updated by Sandy - confirms blog-clearing is in-game.
09:20: Blogger-logo.JPG Sandy's Blog disappeared (posts disappeared one-by-one). Posts are archived on the wiki.
05:49: Blogger-logo.JPG New Blog post on SandyMayOrMayNotBeFictional.
April 5, 2011:
23:44: Potato.png Two other glyphs found, one that looks like an eye from Amnesia and one that is Super Meat Boy's face.
23:42: Potato.png New glyph found, corresponding with V. From Steve's Photobucket account, llllongjumper. New Glyph also looks like Toki Tori.
23:33: Globe.png There are a ton of TinyURLs we should track as well.
23:23: Globe.png We now have some (presumably fictional) people to track.
23:17: Youtube logo.gif http://www.tinyurl.com/crimeflyerintimidator leads to Sandy's boss's video of the break-in!
23:10: Youtube logo.gif tinyurl.com/stevesaysocelot (and the other SteveSays and ProcyProxy phrases) lead to a YouTube channel closely related to the below blog. A hidden video is of a playthrough of a level of AAAAAAAA!
22:30: Blogger-logo.JPG This blog definitely contains relevant info and was started in March, so likely not fake. Please investigate! Name is from the secret level in 123KI. Torrents of new info are flowing from it.
22:05: Youtube logo.gif The "face" in the new turret video appears to belong to Geoff Keighley, the host of GTTV. He will be doing a show on Thursday, April 7 2011 which will feature a Portal 2 trailer and/or footage.
17:25: Potato.png TF2 updated, adding the Potato Hat for people who have bought the pack. More info at Team Fortress 2.
11:21: Youtube logo.gif Clues found in the latest Aperture Investment Opportunity video. See Portal 2 for details.
10:15: Potato.png 1 2 3 Kick It! is updating for some people; added new content with AppId='98008'
09:30: Unlock.png Toki Tori glyph & text as well as potatoes have been found IN REAL LIFE at the Two Tribes HQ in the Netherlands. HUGE PROPS to JAKE_R for his super sleuthing skillage.
06:45: Potato.png The Ball's glyph and text clue were found.
April 4, 2011:
Unlock.png The braille coordinates in Toki Tori were found to lead to the headquarters of its developer, Two Tribes B.V.
Potato.png The number 16 is appearing quite often. See the anagram puzzles stats, for instance
Unlock.png A potato has been found in Audiosurf when playing Battle of Little Slugger from the Super Meat Boy soundtrack. It has a glyph on it.
Potato.png The chapter "The End" is now playable in Super Meat Boy.
Potato.png Some games updated
Potato.png Killing Floor had an ingame newsflash with code that gave us an interesting message.
April 3, 2011:
Email icon.png Ichiro of Dejobaan gave "1973" as a possible new clue to move forward.
Unlock.png An important username/password combo for Defense Grid was cracked by finding a level shaped into a QR code. This code unlocks one of the profiles in the console. (More info on the Defense Grid page)
Potato.png A message in The Wonderful End of the World unveils that Razer is involved in this ARG.
April 2, 2011:
Unlock.png Heiroglyphics found inside Amnesia The Dark Descent were discovered to be ancient egyptian.
Potato.png More references to potatoes were found in all of The Potato Sack game, as well as Amnesia The Dark Descent
Globe.png The Valve PotatoFoolsDay ARG Wiki was setup by Leveraged & Commandhat. (Thanks, guys!)
April 1, 2011:
Potato.png "The Potato Sack" pack was available for purchase. TF2 hat announced for April 5
Globe.png Several forum members at SPUF and FacePunch realized quickly that this was an ARG, possibly for Portal 2. They began to organize the IRC channel and this wiki.
Potato.png #PotatoFoolsDay updates released. Updates contain odd references and media related to potatoes.
Well, what say you? It seems a bit elaborate for a one day April fools thing :O