Thanks for the useful information!
I hadn't heard of Zelda: Return Of The Hylian before now. It seems only the first of the trilogy was ever ported to Dreamcast according to what I could find online. However this game / engine looks like it might be an excellent starting point for creating a new RPG that can run on computers and consoles such as the Dreamcast!
Zia and the Goddess of Magic might be a good game, but I'm afraid it doesn't have an open source engine, so it wouldn't be useful for a third-party such as myself who is looking to create a new RPG.
I have tried using the Titan Game Engine, but alas, it is too early of a project to be useful for making RPG's. You see, while I appreciate what the developer is trying to do (making a friendlier front-end to KallistiOS so that people can more easily make Dreamcast games), and it is a laudable goal, the software is currently not developed enough to be very useful.
For example, if you can get the Titan IDE 0.6 to work, then if you try to make an RPG, then the most which the RPG template is capable of is making an image appear on the VMU, painting the ground with walkable and non-walkable tiles, and walking your character around them. That's it. You can't add more characters, enemies, treasure, weapons, fights, dialogues, menus, saving and loading progress, or anything else to the "game." You can't even make a winnable game unless you are making a walking simulator that doesn't even show a "You Win!" message when you reach the end of the map. Even the documentation is sparse and tutorials are few. Perhaps one day Titan IDE will reach the point where it can be used to make complete, full-featured games, but it is not there yet.
However, all of this info is helpful in finding my way to creating a new video game for the Dreamcast!