You can try Flux for free, it will have a small watermark but no limitations. Please let us know what you think, we're dying to know!
Don't forget to look at the manual and videos first, it will be much easier to get into Flux!
Flux 2.0.2+ supports Playmaker, in order to enable it make sure you have Playmaker for Unity 5 in the project and add the compile flag FLUX_PLAYMAKER in the player settings.
Note that Flux 1.x requires Unity 4.5+, and Flux 2.x requires Unity 5.