Paradox Entertainment is the keeper, so to speak, of the property that is Mutant Chronicles. They are what became of Target Games AB when it dissolved. They hold all the former Target Games properties.
Excelsior has been granted a license to care for and develop content for Warzone and Chronopia.
Paradox Entertainment is who you must go through to get permission (I.E. a license) to develop things based on the Mutant Chronicles that you want to make money with and that have not already been licensed.
I don't believe there is a Mutant Chronicles video game though... unless you are referring to Doomtrooper for SNES and Genesis.
Paradox Interactive was developing Warzone Online for Xbox, which was halted. They are another off shoot from the original Target Games AB company. I'm not completely sure if they are still a subsidiary of Paradox Entertainment, but they no longer have anything to do with any of the original Target Games properties, so I assume not.
A company called Imaginations was developing an MMORPG under license from Paradox Entertainment, but they cancelled it due to lack of a publisher.
I would also assume (I’m doing a lot of this and sometimes that’s dangerous) that Excelsior might be made up of some remnants of Heartbreaker which, back in the day, was publishing the RPG, CCG and Warzone here stateside until it was "dissolved" too.
If it is true I would assume that Paradox Entertainment, originating from Target Games, would continue its relationship with those that were once a part of Heartbreaker and give all the same licenses to Excelsior. That would include the RPG and the TTG, and would include the KULT universe as well (I think Bryan Winter owns the rights to the CCG. If that’s the case that system could not be used and would have to be renamed and built from the ground up as a new game).
The kicker though is that Heartbreaker just had to publish here while Target Games developed content and published in Europe. Excelsior is now developers and publishers. That’s a huge task and would explain why the RPG is on the back burner, not to mention the decline of RPG sales in general over the past few years.
I think thats the majority of it... if not, please clarify and set my record straight.

Should i know this stuff...

Thanks in advance.