Guild of Writers

How was the rain effect on Relto accomplished? How could I go about implementing it in an age?

Rain is particles. Take a look at my tutorials on that over at the GoMa:

http://www.guildofmaintainers.org/Forum ... 154&t=1677

If by Relto you mean, turning the rain off or on, that would depend on many things, mainly on what it is you want to do. You can disable and enable particles with a responder. How you trigger that responder is up to you: clicking on something, entering a region, or using a python file mod.

Essentially it is a particle effect. In the case of Relto I'm not sure if those are large particles with a transparent textures on it or just very thin particles. If you have never tried those yet, I suggest you look up some tutorials on Max particles. We don't have much documentation on those yet, but Andy has made an article here that will at least give you an overview of how to add some to your Age. Particles aren't very complicated, they look intimidating at first, but for the most part you'll just need to tweak parameters around.
Depending on the design and size of your Age there can be some subtleties to it. There are two essentially:
1) There may be some areas where you will want to block the rain: inside buildings/caves etc. I'm not sure how to do that in Plasma; I guess there are particle-specific colliders to block them.
2) If your Age is larger than Relto for performance reasons the particle generator should not cover the entire area of the Age, it should be much smaller and it should follow the camera around. To be more precise it should be in front of it, and cover a large enough area that it looks convincing. (around 20 feet should be enough). I've no idea how to do that, but some Python will certainly be involved.

[edit]ha, Andy was faster.