HLAE History
The technical history can be obtained from the changelog included with each download. Please be aware that the following content was written by the HLAE team and thus lacks objectivity.
The original Mirv Demo Tool (the old name of the HLAE tool) dates itself back to the 2nd of May 2004. The by now first known release date is one of the v0.2 updates on 11th of July 2005.
Until version 1.0, MDT was developed by Mirvin_Monkey only. He began writing it for an IRC friend, who was going to do a video about a Team Fortress Classic competition called ECTFC. The motivation was to make a plugin that would let the friend do effects that hadn't been seen before in a GoldSrc gaming video.
He started off with a simple empty OpenGL hack example framework that he found, and wrote everything into that, but Valve kept changing things, so he had to keep rewriting the hacking/injection-related code.
Version 1.0 and versions prior to that already had several of HLAE's current features: i.e. matte effects, depth images, wireframe effects, zooming and entity tracking.
In the first quarter of 2007 (shortly prior to 1.0) Mirvin_Monkey also added a fix that allowed the use of campaths in Team Fortress Classic, which would have been limited to CS 1.6 / CS:CZ only otherwise. This fix was the successful result of an ongoing and exciting technical conversation between Mirvin_Monkey and ripieces (now known as dtugend), the author of the campath tutorial that was released in December 2006 - a tutorial that covered Valve's Half-Life DemoEdit tool, which was mostly unknown to the movie-making public until then.
This first collaboration between Mirvin_Monkey and ripieces (dtugend) was the key event for the ongoing maintenance and development of MDT, which is expressed in the submission of the full MDT 1.0 (1.0.57.0) source code to the code versioning system on the 28th of June 2007.
This key event not only allowed to continue the MDT development (updates when MDT broke due to changes in the Half-Life engine), but also to improve and extend existing features (e.g. logarithmic depthdump) and to add new exciting features such as sound export.
In August 2007 nemoic joined the team, who was mainly responsible for propelling and coding the idea of an MDT GUI.
The team member msthavoc joined in the same month and helped the team with testing, developing tutorials, documentation, suggestions, maintaining community relations and developed plugins that connected camera motion data to other programs such as 3D Studio Max and Cinema 4D.
Also the connection between the movie-making community and the MDT team grew closer, since features like a forum and a wiki were added. Not to mention most of the team's members were and are closely connected to the movie-making scene in one way or another.
In March 2008 the project changed its public name to Half-Life Advanced Effects (HLAE) in order to reflect the changes in the past and to express the targets for the future.
In September 2008 the HLAE team obtained the domain advancedfx.org in order to get the project more organized and centralized.
Along with the CS 1.6 player base, the GoldSrc-based movie-making scene saw a decline in popularity in the late 2000s. The HLAE project started supporting CS:S with limited camera motion data features in late 2009, and CS:GO later on in 2013. In late 2014 the primary development was focused on adding new features to CS:GO, and HLAE kept supporting CS:GO until the game was replaced by CS2.
If you have contributed to the Wiki, you can make an issue in contrib repository in order to be added to or updated in the credits.
A list of things missing is in the Wanted article.
(Half-Life 1, Counter-Strike 1.6, ...)
(CS:GO, ...)
(Counter-Strike 2)