VERGE

VERGE is a Game Creation Engine: A progam that exists to help you make games.

It was started in 1997 by Benjamin Eirich (aka vecna) and Brian Peterson (aka Hahn) to make 16-bit style RPGs akin to the Phantasy Star and Final Fantasy series.

Since then, it's been used to make pretty much any genre of game from the Super Nintendo / Genesis era.

Open Source
The current iteration of VERGE is open source under the BSD license. The repositories for it (and related projects) are as follows:

verge 3 - The main engine
psdmap - A tool to convert Adobe Photoshop image files into VERGE 3 maps.
maped2w - The previous version of the map editor, built in Allegro
v3 tiled - A set of tools for converting Verge 3 map and tileset formats into tiled-friendly formats, and vice-versa.

Downloads
Awesome Files
Current Engine
VERGE 3 Engine - for PC
VERGE 3 Engine - for Mac

Games to Start Off With
The Sully Chronicles (an RPG tech demo) - for Mac
The Sully Chronicles (an RPG tech demo) - for PC
Mademoiselle - A Unique Indie-style Platformer - for PC
Timeless - A Demoscene-style graphics demo - for PC
Lexico - A fascinating 2d immersive puzzle game demo - for PC

Development Tools
VOpenCHR (sprite editor)
psd2map (adobe photoshop map creation)
Maped 3 - a VERGE 3 Map Editor (windows only)

More Info:http://verge-rpg.com/docs/the-verge-3-manual/
Credit:http://www.verge-rpg.com/