Valve has been known to do some awesome and insane things that get their fans extremely happy, angry, curious, or confused. So, here are some of their best moments doing this. There may be others that people remember, but these are the ones I remember causing the biggest reactions. Enjoy! (Edit: Spoony informed me the Backburner's lifeboost was +50, not +75. Fixed that.)

Honorable Mention: The Guard Dog "Update"
Valve posted a strange thank you letter on the TF2 Blog, and this letter linked to an update introducing the Guard Dog class. Due to an ad for 10 TF2 action figures in Left 4 Dead, some people believed this was a real update for the new "10th class." However, when the update was examined closely, it was clear it was fake. Some people speculate that Valve may actually be working on a 10th class or something similar to the Guard Dog, due to the wording of the thank you letter.

10. The Backburner & The Sandman
These 2 weapons, when first released, caused a fair bit of grief for TF2 players. The Backburner scored critical hits with back attacks, lacked the airblast ability, and gave the Pyro +50 life. Pyros with the Backburner equipped ended up having more life than a Soldier, and could easily rip apart a group of enemies, especially when overhealed. The Sandman disabled the Scout's double-jump, and its baseball could stun enemies (invincible or not) for several seconds, leaving them unable to move. These weapons caused a fair number of people to complain about game balance getting shot to hell. Both weapons were adjusted: the Backburner lost the health boost, and the Sandman was changed several times since its release.

9. Left 4 Dead 2 Announced
The original L4D wasn't even a year old when its sequel was announced. Many L4D fans were a bit upset since the game still lacked new campaigns and custom content. Some people even speculated the L4D2 announcement was an elaborate troll by Valve, and the it was only posted to cover up a special update. After some time passed, it was confirmed L4D2 really was coming out, which caused even more rage amongst fans. Some, however, said they'd give the game a chance if it wasn't too expensive. When the game was finally released, there were differing opinions: some felt L4D2 was an overpriced expansion pack, yet others found it better than the original.

8. Left 4 Dead 2 Pre-Order = Special Items
A fair number of TF2 fans were very pissed off when they found out that pre-ordering L4D2 would unlock Bill's Hat for all the TF2 characters to wear. Those who disliked L4D or its sequel didn't feel like paying nearly $50 just to get a special hat. Those who were looking forward to the game got some extra treats: pre-ordering L4D2 unlocked a special baseball bat to use in game, and allowed you to try out the demo earlier. Anyone who pre-ordered through Steam also got 10% off the regular price.

7. The Soldier & Demoman Update
In December 2009, people noticed the Announcer was saying some different things. Some people started going through TF2's sound files to see what was up. On December 9, 2009, a TF2 Blog post was made that appeared to hint at a new update. Then came the Soldier & Demoman update, and with it a 21-page comic, new weapon previews, and 2 big contests. The main contest was a war between Soldiers and Demomen in which they had to kill each other. The character with the most kills at the end of the update would get 4 new items, instead of 3. There was also the propaganda contest to participate in. People had to design posters supporting either the Demoman or Soldier. Three winners got specially-named hats to wear in game, and several runners-up got prize packs. Some of the posters also contributed some free points to the Soldier/Demoman war. The contests were very popular: over 11 000 posters were submitted, and the Soldier and Demoman got over 6 million kills each. However, the kill counts weren't completely accurate, since some people found ways to cheat.

6. The Sniper & Spy Update
Some people speculated that the Spy Update would be "disguised" as an update for another class. These people were proven right on day 4 of the Sniper Update, when it became the Spy Update. This was the first two-class update, and it caused a fair bit of excitement and rage. The newest TF2 video, Meet the Spy, ended up getting leaked on to YouTube, which resulted in several TF2 Blog posts about Robin Walker firing nearly everyone over this "error." The Sniper's new weapons caused quite a few players to complain. Some players threatened to stop playing TF2, or boycott Valve entirely because they made Jarate an actual weapon for the Sniper. Others found Jarate useful and funny, but really didn't like the other two items, the Huntsman and Razorback. Most people complained (and still are complaining) about the Huntsman being able to get some very cheap shots, and the Razorback being nearly useless. The Spy's Dead Ringer watch was also fairly buggy at first, but is now working properly after several fixes.

5. Randomly Dropped Hats & Items
This new system replaced having to earn achievements to unlock all items. The random drops also included hats for the characters to wear, but their drop rate was (and still is) very low. Many people got frustrated when they had hundreds of hours logged on TF2, yet hadn't received a hat. These people usually had duplicates of various weapons, as well. Valve eventually introduced a crafting system, so people could turn duplicate items into things they wanted. Some people were happy with this, but others complained that TF2 was becoming more like an MMORPG.

4. Game Exploits + Achievement Unlocker Programs = Item Loss
In early 2009, some TF2 players found a glitch in the game that allowed them to use one class's weapons on another class. Valve considered this a form of cheating. They quickly fixed the exploit, and also punished those who abused it. The resulting blog post was funny to some, but those who lost items were pretty upset. One week later, another post was made, this time about people using external programs to unlock achievements and items. Before the random drop system was implemented, the only way to get items in TF2 was to get a certain number of achievements for class milestones, which would unlock items. Some of the programs would unlock all achievements, while others would simply unlock the milestones so a player could get the items right away and work on achievements later. Several people complained that Valve was being unfair, some of them threatening to uninstall TF2 and never purchase a Valve product again.

3. Portal Update
Portal was originally released in 2007, and a fair number of people enjoyed it. On March 1, 2010, Valve released a strange update for the game. The news spread quickly, and people who took the time to play Portal or look through its sound files found some interesting goodies. A new achievement was added, and some slight changes were made to the game. Several radios were hidden throughout the game, and if the player brought each radio to a specific area, it would start to play morse code, or other strange sounds. People soon figured out the morse code messages, and found that the strange sounds were actually encoded pictures. Those who looked carefully at the pictures found another code. This turned out to be a BBS number people could get info from if they had certain programs and a 56k modem. Another odd Portal update was released on March 3, which included an alternate ending to the game. People speculated these updates hinted at a sequel to Portal, or another addition to the Half-Life series. An announcement for Portal 2 was made on Steam on March 5, 2010.

2. Pyro's Gender
Since TF2 was released, many players have wondered if the Pyro is male or female, and they still argue about this. Those who believe Pyro is male point out that the character is voiced by a male, has a deep-sounding voice, and doesn't have a female shape. Those who think Pyro is female bring up the purse in Pyro's locker, the Pyro's "girly" run and standing animations during humiliation time, and the fact that Valve employees have referred to the Pyro as "her" in some interviews. Some people have e-mailed Valve and asked them what Pyro's gender is, but no one has received a clear response. Meet the Spy and the Soldier/Demoman update caused more speculation about who the Pyro could be. Some people thought that Scout's mom or Miss Pauling could be the Pyro, but others claimed there was nothing to support this.

1. The Cheater's Lament
Out of all the updates added to TF2, the Cheater's Lament has caused the most rage and flamewars amongst its players. After random drops were added to the game, many people started to complain about hats being so rare. To try and get hats and items faster, some players used an idling program. This program would allow players to idle on specific servers without actually having to run the game. Since the program was an external application, Valve considered it a form of cheating and ended up punishing those who had used it. Unlike the achievement unlocker incident, people lost items permanently if they were earned through the idling program. Those who hadn't used the program were given the Cheater's Lament, a hat designed to look like an angel halo. After the TF2 blog post mentioning what was happening, most of the TF2 community went into a massive rage. Those who had lost their items were extremely angry with Valve, and sometimes took out their anger on those who got the special hat. Those who chose to wear the hat found themselves getting yelled at, not being healed by Medics, and even getting kicked off of some servers. Some people also made special skins for the hat that turned it into various glowing swear words. A few people said that Valve had approved of the idling application, since it was made by the same person who created the TF2 Backpack Examiner. Things calmed down after a while; however, there are still some servers that will kick or ban you if your character has the Cheater's Lament equipped.