Bleem! was a PS1 emulator for the Personal Computer and, most importantly, the Sega Dreamcast. The latter was what caught Sony’s ire. Bleem’s original plan was to put out a catch-all emulator disc for the Dreamcast, much like they did for the PC, but due to memory limitations and some other issues, they found it was easier to put out single-use “Bleemcast!” discs that supported one game at a time. Only three Bleemcast discs were ever released, I believe: Metal Gear Solid, Gran Turismo 2, and Ridge Racer 4. By all accounts, the games seemed to work very well. Boot the Dreamcast using the Bleemcast disc, then swap to the PS1 CD when prompted. Boom: instant remaster.
Sony took Bleem to court. Sony alleged it was illegal and breaking trademarks and this and that and the other thing. Bleem was deemed totally legal. They won their court case. Problem solved, right? Sony did not care. It wasn’t about legality. This was war. Sega was getting an advantage. So, they launched every counter suit in the book. They fought every inch of every technicality they could find.
By law Bleem was required to fight back, and legal battles are not free. For Sony, a multi-billion dollar tech and media corporation, this was but a drop in the bucket. For Bleem, a tiny little company consisting of maybe 3-5 people total, deflecting Sony’s accusations in court would bankrupt them multiple times over. Bleem may have been legal, but Sony still won by technicality. They out-spent them to death. If you’re big enough to be a target, they will get you, because they are still much, much bigger than you are. That’s all there is to it.