Activision is facing another big lawsuit over its tentpole Call of Duty series, only this one has nothing to do with people who used to work on the series. It's to do with a rival developer who owns the right to a name that Call of Duty uses a lot.

Fans older PC shooters may be familiar with NovaLogic's Delta Force series, which around the turn of the millennium was OK, but is now the kind of thing you find selling for $5 in giant buckets in a post office.

Quality aside, Novalogic holds a trademark over the use of the term Delta Force, as well as a logo it designed for the series. These date back to the late 1990s.

Call of Duty fans may be more familiar with the term from Modern Warfare 3, though, as one of the units in the game is called Delta Force. Call of Duty's Delta Force not only uses the same term, but has a logo that's very similar to the one Novalogic has been employing.

But wait, you may be thinking, isn't Delta Force a real thing? With Chuck Norris in it? So how can anybody trademark it? Turns out it's not; while there is a branch of the US Army's Special Ops known as the1st Special Forces Operational Detachment Delta, there is no such thing as a unit officially branded "Delta Force", so Novalogic were free to snap it up (the old Delta Force movie was actually called The Delta Force).

Here's the meat of Novalogic's complaints, as reported on Courtroom News:

"The infringing mark's lightening rod is horizontal rather than vertical and a portion of the delta sign is set behind the dagger blade rather than being superimposed," according to the complaint.

"In single player mode, 7 of 16 missions are designated Delta Force missions, in which the only avatar available to players is 'Frost,' a Delta Force operator," the complaint states. "In addition, players fight alongside a number of non-player controlled characters. Several of these characters are members of Delta Force."

"In multiplayer mode, 7 of 16 mission maps have 'Delta Force' as one of the two factions that the player can select," NovaLogic says.

"At the time of this writing, Activision has released 6 additional multiplayer maps with infringing content. Activision plans to release additional content through their 'Elite Content' feature," it added.

"Despite Activision's irrefutable knowledge of NovaLogic's superior trademark rights, Activision created knockoff marks that are nearly identical [to] NovaLogic's design and word marks," according to the complaint. "Activision then shamelessly inserted these infringing marks throughout its competing first person military adventure video games.

"As if this were not enough, Activision has in-turn licensed the infringing marks to Defendants Voyetra Turtle Beach then shamelessly ('Turtle Beach'), Microsoft Inc. ('Microsoft') and the BradyGAMES division of Penguin Books ('BradyGAMES') without NovaLogic's permission. As a result of Activision's unauthorized licensing, Turtle Beach and Microsoft have created special editions of their products where the overall look and feel is entirely dominated by use of the infringing marks. In addition, BradyGAMES, a creator of videogame strategy guides and books, has reproduced NovaLogic's marks in its publications relating to defendants' game."

In terms of what Novalogic wants out of all this, the developer says it is seeking unspecified damages and "an injunction for trademark infringement and unfair competition."

Call of Duty Accused of "Shamelessly" Ripping off Another Series, Legal Warfare Ensues

Video Game Maker Says 'Call of Duty' Copies Old 'Delta Force' Logo [Courtroom News, via Polygon]