DH Simulations is a new development team from Germany, which are obviously very passionate about aviation -- especially helicopters. They have realized it was time to bring the EC-135 (or H135 as it's now called by Airbus Helicopters) to the newer, higher standards that a new sim such as P3D allows nowadays.
They have chosen the EC-135 for being one of the most popular models in use in Europe and are working hard on this project, for quite some time. It's curious because, according to them, they were working on this project as something private but then they realized this should be something to be put out there, for the community. Do note, though, that this is a payware project.
DH Simulations is using the most recent techniques in every area of addon development to bring this project to live and, if everything goes according to plan, it should be a very high quality project indeed.
As far as variations go, these guys are planning on developing different variations, from around the globe as well as adding the ability to choose between different equipment, cockpit and both exterior and interior designs.
You should expect to see operator such as ADAC,BMI,Christophurus (Austria), German Police, Federal Police, HTM, Auit Alpin, State troopers, and the Gendermarie. DH Simulations says more will follow.
What about systems? Well, using their own words "we use the slogan 'as real as it gets'". They are in touch with real pilots and are adding all the real functions and features you can find in the real EC-135.
Gauges are being developed in C++ and all displays will be dimmable.
Of course, we should expect the usual simulation limitations of P3D, which is a shame. Hopefully, these folks will be able to overcome some of the obstacles. There's something else that you should know: the FSX version, although partially supported, will lack some features like a FLIR.
Let's keep our fingers crossed and hope this project comes to live with the quality DH's planning on.
Meanwhile, you can follow DH Simulations on their Facebook page. Check it out!