Background Art (Evolution)
Before the retail release, the background for the main menu was a texture image instead of a 3D background, different background textures was used throughout development
Contents
2003 Leak
All background images found in the 2003 leak
Version 1: City 17
located in the leak under gfx/shell is a file named "splash.bmp", this artwork depicts a very early version of city 17, back when it took place in America, as the artwork depicts American-style buildings and skyscrapers. The artwork itself is from 1998 (based on the copyright info on Splash8bit.bmp), meaning that this artwork was created during the Pre-Pitch Era. Based on how it's formatted as the non-steam/retail Half Life 1 and how other files in this directory are pre-steam Half Life 1 menu remnants, this background has likely been used very early in development, likely between 1999 to early 2000, which was during the Hyper Era. It should also be noted that the bottom right of the artwork could very well be one of the earliest logo for Half Life 2.
Oddly, Splash8bit.bmp, which is located in the same directory, depicts the same image, but with a copyright noticed on the left-hand side
This background art also has a loading texture as well located in gfx/status called "loading.bmp", which, just like Splash.bmp, is also formatted as the non-steam/retail version of Half Life 1. The texture itself appears to be an almost exact copy of Splash, except now it's black and white, and has text that says "Loading" in yellow color.
An oddity of the loading image is that, while appearing exactly the same as Splash (minus the obvious differences explained above), it does have 1 new difference, the "2" on the logo is much bigger than on Splash.bmp, which might suggest that these versions are earlier iterations of Splash.bmp
Another oddity is that 2 other background files exist in this directory as well besides loading.bmp. The first background is titled "gordon_loading.bmp" which, besides the new file name, appears to be an exact copy of loading.bmp. The second background, titled "Logo.bmp", appears to be the same image as loading.bmp but without the loading text
gfx/status
Version 2: Gordon Freeman
Located in the leak under materials/launcher/ is a file called "background.vtf" and "background.vmt". This image is considered by some to be the most popular beta menu background, as it's used in the majority of the Megabuild. The artwork itself is a modified image of a concept art of Gordon created by Dhabih Eng. The artwork depicts Gordon with a blur effect on the right side of the screen, with the left side being empty (likely for the menu buttons). Unlike the concept art, no other characters or objects besides Gordon appears, and Gordon's face emits a yellowish-white, while his torso emits an orangish-brown. The dates for this background being used is believed to be from late 2000 to 2002, which, if true, would make this the longest surviving background from the beta.
In the 20th anniversary E3 2002 upload by valve, it shows this background being used for the build, meaning that this background is confirmed to still be used during May 20, 2002
Concept Art
Version 3: Citadel
Located in the leak under materials/console is a file called "console_background.vtf" and is the background that is used in the leak. The artwork depicts the Citadel towering over the camera on the right side, and at the bottom is the Combine Smart Barrier with the Half Life 2 logo on said wall, Every object is surrounded with a thick dark green fog. Just like with the Gordon background, it is assumed that everything is skewed to the right side as to not have the menu buttons obscure the artwork. The only thing on the left side is the Valve logo on the top. This background is believed to have been created in early 2003, and since this is used in the leaked build, it is currently unknown when they removed this background
One thing to note is the background color, which is dark green, as the beta menu UI is also green, possibly being a design detail. This could possibly mean that Half Life 2 switch from retail Half Life 1 menu to Steam Half Life 1 menu when this background was implemented, however this is unconfirmed.
Retail
Different backgrounds found in the retail release (note: At this point, backgrounds now use a 3D map)
intro.bsp
Located in the retail build of Half Life 2 is a map called "intro.bsp", this map is an early version of the intro cutscene, sometime during or after E3 2004, as the opening cutscene is very similar to E3 2004, however intro.bsp includes the "right man" line and has the train scene, which isn't in E3 2004's intro cutscene (however, something to note is that it is used at the end of E3, so there's still a possibility that it was used in the intro at the time)
However, when opening the map using the map_background command, you will instead get what is believed to be an early version of the first background menu map. This background displays the rooftops sections of Point Insertion. Oddly, this background map will play Ravenholm's starting music.
The 20th anniversary update had broken this map, as now the skybox is missing, and the bird poop texture is now black.
In the game files, there is a blurred image of this background, further providing evidence that this was supposed to be an early background map.
Final
The final version of the background is unique from the beta, as now it's a 3D map rather than a 2D background, furthermore, unlike the beta, the background will change depending on what chapter your last save was
For example, the starting map depicts the outside of the train station, with ambience and animation playing in the background.
It should also be noted that the UI is now grey, rather than a dark green
Other
Backgrounds that was found from external source
Dark Messiah of Might and Magic: Blurred HL2 Logo
Dark Messiah: Might and Magic is a game developed by Arkane Studios and published by Ubisoft in 2006. It is notable for being the first third-party source game to be released on the Xbox 360
However, in the game files, there appears to be remnants of an unused console background for Half Life 2. It depicts the Half Life 2 logo on the bottom right, glowing yellow with a blur effect, while the background appears to be dark red, with lines and circles barely visible
It is currently unknown where this background was used during development, that is if they used it at all. The Dark Messiah tcrf page claims it was shown on E3 2003, however no source has been provided. The Megabuild team decided to put this background on the E3 2002 mod, however, the 20th anniversary upload of E3 2002 shows the build still using the Gordon Freemen background, proving Megabuild's hypothesis to be false