Attached Link: Silo3D on Steam - $59

I noticed that Silo3D ver 2 is for sale on steam for $59.... I thought Silo3D was a dying product? Does anyone know if there will be any future versions of Silo3D? 

The price certainly sounds enticing but I already have Hexagon and Groboto which appear to be abandoned apps...

Also is steam some sort of a runtime environment that is a prerequisite to run Silo3D which must be installed on your computer?

Thanks kindly....