Valve has a few reasons why Half-Life 2: Episode 3 never happened

Valve has explained why we never got Half-Life 2: Episode 3.

Valve Explains Why Half-Life 2: Episode 3 Was Never Made - IGN

Steam users are attacking Dota 2 because there's no more Half-Life - Polygon

Half-Life 2, Episode 3 The Closure released news - ModDB

Half-Life 2: Episode Two - Wikipedia

Valve, seriously, where is Half-Life 3?

Half Life 2 Episode 3 Synopsis Posted (Spoilers?) - Gaming - Level1Techs Forums

Here Is Every Mod That Attempts To Make Half-Life 2: Episode Three feature - ModDB

Half-Life 2: Episode 3 creator reflects on reception, one year after release

Will Valve Ever Release a Half-Life 3? Ten Years After Its First Announcement, Signs Point to No - The Atlantic

Why Valve Gave Up On 'Multiple' Half-Life 3s