When speedrunning a game, it's very important that you pick the right version of it, because of the glitches that are only available on a certain version.
|Version||Build||Protocol version||Date||Notes||Runs using this version|
|0.52||315||Unknown||September 4, 1997||Half-Life Alpha|
|18.104.22.168||738||N/A||November 1, 1998||WON, no Bunnyhop speed cap||N/A|
|22.214.171.124||N/A||N/A||N/A||WON||Half Hour Half-Life|
|126.96.36.199||N/A||N/A||N/A||WON, Bunnyhop speed cap|
|188.8.131.52||3248||47||September 15, 2005||NGHL|| HL21
|1.1.2.-||4382||48||October 23, 2008||Protocol 48 release|
|184.108.40.206||4554||48||June 15, 2009||Last version before Steampipe (scripts w/ _special work), works with Steam
|220.127.116.11||6027||48||April 27, 2013||Steampipe beta
Last build w/ _special
|Latest Steam version||6153||48||August 29, 2013||Steampipe|
WON versions up to 18.104.22.168 don't have the bunnyhop speed cap, but they also don't allow the player to exceed the 100fps limit and _special scripts only work with 22.214.171.124, which is useless because that version already has the bunnyhop cap.
|Build||Engine||Date||Notes||Runs using this version|
|2187||Source (6)||November 2, 2004||HL2DQ|
|2455||Source (7)||July 28, 2005||HL2DQ|
|2707||Source (7)||April 6, 2006||Plays HL2DQ demos recorded on build 2455 and HL2 DQer was made with this.||Old Engine RTAs/SS runs|
|4044||Source (7)||December 3, 2009||Last version to run on Source Engine.||HL2DQ-er|
|4295||OrangeBox Engine (15)||August 11, 2010||Half-Life 2 port to OB Engine|
|5135||OrangeBox Engine (15)||November 28, 2012||Last version before Steampipe.
Airboat stops on every map load.
|5298||OrangeBox Engine (24)||May 10, 2013||First Steampipe build|
|Latest version||OrangeBox Engine||Steampipe|
Half-Life 2 build number is the number of days since November 7, 1998.