Lambda Fortress

Lambda Fortress may refer to many different TF2 Sourcemods that aim to make the TF2 classes fully playable for co-op across Half-Life 2 and other Source campaigns.

• Lambda Fortress (Nicknine): The first iteration of the Lambda Fortress mod created by Nicknine.
• Lambda Fortress: Extended: The second iteration of the Lambda Fortress mod that was forked off of Nicknine's Lambda Fortress with various additions.
• Lambda Fortress (CoaXioN): The current iteration of the Lambda Fortress mod, being developed by CoaXioN, built off an early version of Lambda Fortress: Extended that aims to fix the issues the mod had and bring it up to modern standards.

Although not referred to as Lambda Fortress, Fortress Connected is another mod built off of Lambda Fortress: Extended with the aim of extending support to other valve games/mods including Left4Dead, Counter Strike: Source, and more.