Well, PC Gamer decided to get a few more details about this lawsuit, and did a little bit of digging into the situation and the legality behind it. Talking with Rune 2 executive producer Matt Candle, they were able to learn a little bit more about the "mountain of evidence" that Ragnarok has on Bethesda, even if Matt refused to go into too much detail outside the courtroom.
"In our situation, Bethesda took a sudden interest in Human Head only after playing an early version of the Rune II. And after apparently very little diligence, Bethesda and Zenimax acquired Human Head in such a way that it was impossible for Human Head to deliver the game it promised to us and to the fans. There is no doubt that Human Head pitched a game concept and plan to us (Ragnarok Game LLC) that intended to peel market share away from Skyrim by offering a comparable experience but with coop functionality....
...Since filing this lawsuit, we have learned new details that have dramatically strengthened our case. On one hand, it is shocking and disappointing to realize the lengths they went to sabotage Rune 2. On the other hand, it has strengthened our resolve to give our fans a fun game that they can enjoy for years to come."
If Rune 2 was the victim of sabotage, it shows: the game currently enjoys a 49% on Metacritic and a 6/10 on Steam, which you wouldn't expect from a game that claims to be good enough to threaten Skyrim's domination. We'll just have to see if this lawsuit pans out... and if Rune 2 can be "un-sabotaged" into a game that would justify this kind of paranoia.