Hephaestus is a freeware computer role-playing game construction kit (often called an “RPG maker”). A map editor is included, and scripting is done in the Java programming language. Hephaestus is written in Java, and therefore runs on every platform.

You’ve wanted to make your own computer role-playing game all your life. Hephaestus 2 makes it easier than ever to make any adventure you can imagine. Use your own art and sounds, or use the standard libraries. Make “static” maps with the map editor, or create your maps entirely with code – even making mazes and dungeons that are different every time you play. There’s never been a better time to start writing your own CRPG!

Hephaestus 2 now includes the post-holocaust horror adventure, Umbra! After the Great Old Ones return to reclaim the Earth, the few survivors cower in towns hidden in the wilderness, or have given themselves over to madness and worship of inhuman gods. You start out alone and helpless, but can rise to strike back, and perhaps return Earth to humanity!

Being in Java this works under linux and mac too.

LINK