So, on the JRPG I've been working on, I have more or less finished the battle system.

http://files.byondhome.com/TheMagicMan/jrpgfinal.png

Pic related.

It is a fairly complex system, with a lot of factors to take into account, allowing for lots of strategy (and the game will be very hard, so you will need to be smart).

And, even though I am tooting my own horn, I'd say that is is technically the most impressive system of it's kind made with BYOND (which I'd say previously belonged to another, similar system I made in W-BAT).
The downside to this is, the system makes use of things like alpha transparency for interfaces, image blending and color mapping. These aren't downsides in their own right, since they make things look pretty cool (my mind still gets blown at the effect that plays when you kill an enemy. I've tried like 50 times to screenshot it, but some sort of optical illusion takes place as well, which makes taking a screenshot hard as hell). But from previous testing, a lot of BYOND users have bad computers, that struggle with these kinds of things or simply cannot do them. If you are one of these people, you probably wont be able to play the game. And there will be a lot of other aspects of the game which do make use of these features as well.

Although I say the system is finished, it is still lacking content.
There is no enemies other than ones I use for testing.
There is no animations at all yet, since they're a pain to make.
And though there is some abilities to use, the majority of them have not been added yet.

Most of this can be added with minimal effort as the game is made however.

Once I polish things up, and add a few of the above, I may make a small demo so people can test things out.