This is based on Haven Prelude, a flash game that was never able to generate enough of a following, despite its high quality.

Personal diary of an unnamed Imperial officer
Classified by order of the Inquistorius
Until recently, it was generally believed that the heretics in this region, being without shipyards of note, could never hope to compete with the blessed and righteous Imperial Navy, blessed by the Omnisiahh and our undying Lord.
We have stood by this position.
However, I must confess that I have abandoned this position after our recent battle with "Cainite" forces, where they used ships of unknown design and origin to utterly annilate our forces. Their ships exhibited superior speed, maneuverability, shielding, armor, and firepower. Overall, the Imperial Navy was outmatched.
What the frak happened...?

Adeptus Mechanicum Report # 00110001 00110101 00110110 00110111 00110100 00110010 00110110 00111000 00111001 00110101 00110100 00110100 00110110 00110101 00110100 00110100 00110111 00111000

The hereteks of Slawkenberg have either(1%) mastered micro-FTL travel or (99%) found the STCs or remnants of Missing Object of Reverence 37372 (Fleet 68219 of Old Earth, or Dark Star fleet)
Dark Star fleet is a well-rounded fleet that fought with distinction during the opening days of the Age of Strife, and contains both unique prototype ships and venerable vessels that were ancient even by the standards of the time(ERROR! Date unknown!).
Important known vessels include the following-
TNS Dark Star : Heavy Cruiser, Flagship. Heavily-armoured, with strong advanced void shield contemporaries that can be overclocked to render the ship impervious to all missiles and projectile weaponry. Effectiveness of strike craft against Dark Star presumed to be low. Like almost every vessel in the fleet, carries Dark Age torpedoes, with the flagship being implied to carry STCs for all torpedoes used by the fleet.
TNS Vagari : Dreadnought, "Pride of the Terran Navy". Dreadnought fitted with reinforced shields and heavy armor, with similar overclocking abilities as TNS Dark Star , along with heavy weaponry and torpedos.

TNS Beijing : voidcraft/aircraft carrier with known repair capabilities, point defense melta, and lack of torpedoes. Known capacity is estimated to be at least 100 craft, with guesses being around 250.

TNS Scott Smith : prototype stealth ship able to remain undetected regardless of distance. Carries prototype superheavy missiles/torpedoes.

TNS Veloz : light cruiser capable of micro-FTL.

Other vessels are present, having one of every type of vessel used by the Terran Navy at the start of the Age of Strife. We must acquire it by any means necessary before anyone else.

Expedition has been dispatched in order to neutralize Inquisitorial assets and put our Mechanicum in a position to seize Imperial Naval assets to retrieve the fleet.
On the next engagement, all officers are to be rendered unconscious while we perform our holy work in order to bring these ships back into the fold. When signal is given, all naval crews will be disposed of, and Imperial ships will be directed to engage with Dark Star fleet so that we may board the venerable vessels and seize them in the name of the Machine God while our ships draw the fire of the hereteks. The disposed crewmembers will be be made into servitors, in order to better accomplish this task. For the flesh is weak, and the machine is eternal.