Blizzard Launcher

Blizzard Launcher was a utility application introduced with patch 1.8.3 to ostensibly provide news links and a minimal set of pre-launch configuration options for the actual game and the patch downloader. Behind the scenes it would also theoretically provide some measure of scanning and protection from trojan viruses and third party cheat programs.

The Blizzard Launcher has been superseded with the release of the Battle.net desktop app.

Design change
With patch 3.0.8, the launcher was redesigned with a new look. Also added to the "Options" menu was a bare-essentials "Game Preferences" panel, "Downloader Preferences" panel, and a "Parental Controls" link to the "WoW Account Management" website.

With patch 4.0.1, the launcher was redesigned and themed for the expansion Cataclysm. With patch 5.0.4, it was redesigned and themed for the expansion Mists of Pandaria.

Features

 * Act as a scanner and warn the user of the malicious software.
 * Provide news links about WoW and Blizzard.
 * Control the options of the Blizzard Downloader in regards to pre-patching.
 * Update the game. New in Patch 2.1
 * Options button to show options panel.
 * Minimal pre-launch game preferences.
 * Patch downloader preferences.
 * Button link to Parental Controls web page.
 * Public Test button link to PTR login web page.
 * ? button to show web links panel.
 * Community page web link.
 * Forums page web link.
 * Blizzard Store page web link.
 * Technical Support page web link.
 * Parental Controls page web link.

Controversy
There was a bit of controversy regarding the Launcher as it was scanning the computer for malicious software, which some people believed to be an invasion of privacy.

Patch 4.0.1


In Patch 4.0.1, the launcher was updated to "stream" installation and patch data. The new launcher is broken up into three stages of download progress:


 * #FF0000 Core game, or 5% of content, is being prepared. You cannot enter the game at this time.
 * #EEBB33 Base game, or 70% of content, is not completely applied. You can play, but your game experience will not be ideal. You should ideally have 1 MB/sec or better when choosing to play.
 * #00FF00 Extended, or 25% of content, is almost complete. You may begin playing at this stage with few game issues. You should ideally have 1 MB/sec or better when choosing to play.

The Updater and Downloader have been integrated closely into the Launcher, resulting in less application switching when patching and installing.

The reasoning and utility of the launcher is based on the fact that, for instance, if a large raid instance is being added to the game there's no reason why the players shouldn't be allowed to access the game world and play as it downloads.

Patch 4.3.2
Patch 4.3.2 brought 2 major changes to the Launcher functions.

The first being "Repackaging Game Client Data". Pre 4.3.2, Blizzard would only repackage Data folder .MPQ files into fewer (but larger) data .MPQ files when an expansion released. With 4.3.2, Blizzard made a commitment to repackaging the Data folder more often.

The second change was the additional of "Verify/Repair Game Data". Pre 4.0.1, this feature was available via the Repair.exe file located in the main WoW folder. When Blizzard switched to the Streaming client in 4.0.1, the function of the Repair.exe file switched to repairing only the .exe, .dll and other minor files located in the main WoW folder - the only way to repair game data was to log into the game, and have the client stream non-corrupted data. This however caused lag-related complaints, and even caused issues where users would disconnect from the game due to the sheer volume of uncorrupted data needing to be streamed. With the addition of this option to the Launcher, users can once again repair their game files while not in the game.

Patch 5.0.4
In the Mists of Pandaria launcher introduced in patch 5.0.4, the last phase in patching has been renamed from "Playable" to "Optimal", and the PTR options are now under the "Options" button.