Not much to the story. The server released an info, that the Sturmtiger is being supertested, alongwith this picture:

It's a fake.

My contact confirmed no such thing is being supertested. Additionally, screenshots from supertest contain watermarks, visible when the picture is blue-shifted in photoshop to identify leaks. This one doesn't have it. Most likely a changed model. Same goes for the "E-25".