Hi
There are Popeye and WinChloe: two programs supporting fairy pieces but only orthodox chess boards.
There is Board Painter, a program developed by my team (you find it on my website under tools): supporting Classic Boards of any size and also it now supports special boards of any size with extra squares on corners (like in Omega Chess). Many fairy pieces but not Nightriders for the moment because this tool was developed for special purposes. it's open source, so you can develop it the way you like, add any piece you want and share.
Enjoy
Zied
Wow, thank you !! Board Painter is really great and amazing!! I like it very much. I hope there will be more unique pieces developed. well, some are too alike but it's already very good.
Does anyone know what program has fairy chess pieces, such as grasshopper, knightrider, amazon... and can create problem diagrams like the one shown below (maybe even on a non-standard board)