If you are looking forward for an open source development tool to develop graphic adventure games, then Adventure Game Studio (AGS) is just your thing. This Game engine basically targets Intermediate level game designers. It was basically built to develop point and click games.
In order to set up the most features of game with scripting language written in C language AGS combines an Integrated Design Environment (IDE). It is a 2D oriented Gaming Engine. The target platforms are Windows and Linux.
It was originally developed by Chris Jones back in 1999, AGS was made available as open source in 2011 under Artistic License 2.0.
Platforms Supported: Windows 7, 8, 10, Vista, XP and Windows 2000 (Linux, Mac and other ports also available for playing, not developing)
github
Further specifications
- It supports the games with a graphic range up to 256 colors
- It supports games with more classic look (a resolution of 320×200) to a more modern looks (resolution of 1600×1200)
- It supports many graphic filters including:
- 2x nearest neighbor
- 3x nearest neighbor
- 4x nearest neighbor
- hq 2x
- hq 3x
- Video Formats: AVI, WMV, FLC, OGV (Ogg Theora); full-screen only
Games Developed using AGS Engine
Resonance is a third-person point and click adventure game. 
The Journey Down: Over the Edge game: Chapter one. 
Winner of the MAGS competition for June 2019. Help a hungry customer get an ice cream! 
Apprentice II: The Knight’s Move:
Heroine’s Quest is an adventure / RPG hybrid.
Useful Resources
- AGS Engine Website: https://www.adventuregamestudio.co.uk/
- List of Games developed using AGS: https://www.adventuregamestudio.co.uk/site/games/
- Source Code: https://github.com/adventuregamestudio/ags
