Through SRB2's development, several releases, or versions, have been made. A major version contains a multitude of improvements over the last version, such as changes of the game engine or the addition of new levels. Minor versions usually consists of bug fixes and smaller additions. The below is a list of major versions. Information on minor versions is included in the article for the major version they belong to.
- 1 Pre-demo versions
- 2 Demo versions
- 3 Final Demo versions
- 4 Post-demo versions
- 5 External links
These releases of SRB2 precede the first actual demo of the game. They were similar to a tech demo, as they did not include any of the current levels and were mainly used to show off the state of the game engine and expand on it.
- Original release date: unreleased, developed March–July 1998
SRB2 TGF was the first version of SRB2. Unlike the current incarnation, it was a 2D game created in The Games Factory, like its predecessor. The idea was discontinued when SRB2 was moved to the Doom engine in 1998.
- Original release date: October 31st, 1999
SRB2 Halloween was the first SRB2 version made on the Doom engine. It consisted of one Halloween-styled level showcasing basic elements of Sonic gameplay.
- Original release date: December 24th, 1999
The successor to SRB2 Halloween, SRB2 Christmas, included several levels and had a Christmas theme. Five versions were released between late 1999 and early 2000, each progressively expanding on the game's engine to make it more Sonic-styled.
These demo versions started to add actual SRB2 levels intended for the final game. They also expanded on the engine and introduced netplay, as well as other substantial game elements.
- Original release date: November 2000
Demo 1 was the first version to start work on the Single Player campaign. It contained only one map, an incomplete version of Greenflower Zone Act 1.
- Original release date: March 5th, 2001
Demo 2 introduced Greenflower Zone Act 2, Greenflower Zone Act 3 and Techno Hill Zone Act 1, bringing the total number of playable acts to four. Knuckles was also added, but did not yet have his own sprites.
- Original release date: June 23rd, 2001
- Original release date: December 25th, 2001
Demo 4 introduced unlockable and secret content, such as Special Stages, Castle Eggman Zone, and date-activated secrets such as Christmas mode. Capture the Flag was also introduced in this version. In Demo 4.1, Knuckles received a new set of placeholder sprites to replace the ones he used previously.
- Original release date: March 8th, 2002
Demo 4.35 (originally Demo 4.32) was an update of Demo 4 that ported the game from Doom Legacy v1.30 to v1.32. It also introduced the character select screen, and replaced most of the Special Stages from Demo 4.
- Original release date: March 2003
This was a multiplayer-only demo released exclusively to the Sonic Amateur Games Expo (SAGE) to show off the new multiplayer features of Final Demo 1.01, which was then in development. Among them were weapon rings and the new Chaos gametype.
Final Demo versions
These demos were all meant to be the last release before the final version, which was to be called v1.1. As such, they included only the first two Single Player zones as well as a demo-only version of Castle Eggman Zone. While the core game stayed the same in this era, several major and minor updates were made over the course of several years, all of which were labeled as the final one. This led to a complicated and inconsistent version numbering system, as the version numbers were never supposed to reach beyond v1.09.
- Original release date: June 19th, 2003
These versions introduced Techno Hill Zone Act 2 and Techno Hill Zone Act 3 to the game, and added the previously secret Castle Eggman Zone to the end of the main Single Player campaign. Many unlockables such as Spring Hill Zone, Mario Koopa Blast and Adventure Example were added, and emblems were introduced as a method to obtain unlockables.
- Original release date: January 1st, 2004
This version was intended as a patch to v1.04, but eventually grew to include a number of features of its own. In this version, the multi-thok was removed, restricting Sonic to just one thok per jump. This version also introduced SOC, a scripting language that allowed users to customize parts of the game that were not customizable before.
- Original release date: September 11th, 2005
These versions fixed several critical bugs in v1.08, and added new editing features to the game. Knuckles's ability to glide multiple times per jump was removed, the Chaos multiplayer gametype was disabled, and Super Sonic received a proper set of sprites. An early beta of Red Volcano Zone Act 1 was added as a secret level.
- Original release date: August 19th, 2006
These versions added Time Attack and Circuit levels to the game, as well as new editing features and several other additions. v1.09.4 was the last version in the "Final Demo" series and was current for almost three years.
These releases were made after the "Final Demo" approach was abandoned. From this point on, there is no fixed final version and a new major release is made whenever enough new content is finished. Because of this new approach, releases from this era are substantially more complete and elaborate than before. A new, more consistent version numbering system was introduced for these versions: Releases are numbered as v2.X.x, where X is the major version number and x the minor version number.
- Original release date: February 21st, 2008
This was a semi-private beta version that showcased v2.0's new Match system, much like 2k3 did for Final Demo 1.01. It was released exclusively to the #SRB2Fun IRC channel.
- Original release date: July 24th, 2009
This version introduced nine new stages to the Single Player campaign, increasing the total to 16 levels. The multiplayer system was completely revamped, adding the new weapon system introduced in the Match beta and many other gameplay changes. Many new gameplay elements were added in this version, such as new enemies and bosses, waterslides, reverse gravity, and PolyObjects. Many existing editing resources were restructured, and a new palette was added in place of Doom's default palette, meaning that custom content from older versions will need to be converted to work on this version and later.
- Original release date: March 15th, 2014
This version heavily updated the Single Player campaign, introducing new stages while replacing or significantly editing others. New NiGHTS-themed Special Stages were added to the game, and Time Attack mode was expanded into Record Attack mode. SOC received extensive changes, and Lua was added as a second, more versatile scripting language.
This article gives an overview over plans for future releases of SRB2, including the upcoming v2.2.