Sierra
AGI, SCI, Sierra's AGI / SCI Forum, The Sierra Adventure Hacking Paradise, The Ultimate AGI & SCI Web Site
Adventure Game Studio
Allows creates graphical point-and-click adventure games.
Adventure Maker
Program to make first-person adventure games, such as Myst or Riven. Downloads and screenshots available.
Hungry Software: SLUDGE
Standing for "Scripting Language for Unhindered Development of a Gaming Environment", SLUDGE is designed specifically for adventure game creation and is the language used in Out Of Order.
Insanity Games
Makers of AdvEngine, a graphical point and click adventure game engine in development for games akin to Monkey Island 3.
InterAx Game Engine
Point and click editor for creating simple graphical adventures. Includes screenshots, sample games and editor downloads, mailing list, FAQ, and purchase information.
MAD -- adventure game engine
A free graphical adventure game engine, it is completely script-driven and highly customizable. Mad features an archive system, animated sprites, mp3 playback, and path finding. A beta is currently available.
PAGE: Adventure Game Engine
Development and distribution site for PAGE: Adventure Game Engine and games which are created for the engine.
ScummVM
An implementation of LucasArts S.C.U.M.M. interpreter, used in games such as Monkey Island, Indiana Jones, Day Of The Tentacle and Sam and Max. Includes FAQ, screenshots, documentation and downloads.
SFCI1 Adventure Game Engine
SFCI1 ( Sierra-like Features Creative Interpreter) is a re-visioning of Sierra classic AGI engine. For Win32, Linux and MacOSX
TROIACS - Text Rooms and Objects Interactive Adven
A sierra/lucas style adventure game engine in development.
Twilight Software AGE Developer Pages
The engine allows for the creation and delivery of commercial-grade first-person adventure games and other multimedia.