Crytek is suing Cloud Imperium Games over its use of Cryengine in Star Citizen.

The company's complaints are manifold, and most hinge around Cloud Imperium's switch from Cryengine to Amazon's Lumberyard in the sprawling, in-development space epic.

According to Crytek, it licensed the Cryengine to Cloud Imperium Games (CIG) at a below-market rate because CIG agreed to prominently display of its trademarks in Star Citizen, and because CIG agreed to exclusively use Cryengine.

The former point was a "critical component" of the licensing agreement, Crytek said.

However, since CIG switched to the Lumberyard engine, all traces of said trademarks have been removed.

Crytek was further incensed by CIG co-founder Chris Roberts publicly stating that "we don't call [the video game engine] CryEngine anymore, we call it Star Engine". It also alleges that CIG failed to forward on bug fixes and optimisations to the engine that it had promised to provide.

Complicating things further: Lumberyard, while heavily modified, is based on Cryengine.

Then there's the issue of licensing Cryengine for Star Citizen's single-player spin-off Squadron 42 – Crytek alleges that its agreement with CIG only covers Star Citizen, and that the release of Squadron 42 will constitute a violation of copyright laws.

Crytek is seeking direct damages that "substantially" exceed US$75,000, alongside a number of other damages and injunctions.

Awkardly, CIG co-founder and general counsel Ortwin Freyermuth has previously represented Crytek in similar agreements.

"Notwithstanding that he had confidential information about Crytek's licensing practices that would unfairly advantage Defendants, Freyermuth never recused himself from those negotiations and never resolved that conflict of interest with Crytek," the suit states.

Moreover, negotiations on Crytek's side were handled by Carl Jones, who later left the company to join – you guessed it – CIG.

"We are aware of the Crytek complaint having been filed in the US District Court," Cloud Imperium Games said in a statement.

"CIG hasn’t used the CryEngine for quite some time since we switched to Amazon’s Lumberyard. This is a meritless lawsuit that we will defend vigorously against, including recovering from Crytek any costs incurred in this matter."

For the masochistic, the full court documents are available in full here.

Last month, CIG began selling licenses for plots of land within Star Citizen.

There is no official release date for the game, but the alpha 3.0 version – which CIG considers akin to a Steam Early Access launch – is available now.