It’s basically just Payday in terms of what they own and is relevant, but that’s a hugely successful franchise. I was advocating Starbreeze as a good pick a couple of years ago, because they’d announced they’d started work on Payday 3 after restructuring.
Payday franchise had sold 9 million units in 2014, and Payday 2 has been selling steadily ever since. Steamspy estimates >20 million units sold, but it’s fuzzy at such large numbers. Either way, it’s been a steady earner for the company ever since, and was so profitable it funded their ill advised expansion attempts in the mid 2010’s where they bought several studios and started a bunch of hare-brained schemes for VR and engine development and many other things. All of that was bad decisions, but I’m trying to emphasize that Payday 2 was a huge hit to fuel it.
Unfortunately, Payday 3 publishing has been signed to Koch media (Embracer subsidiary). IMO the optimal time to buy Starbreeze was before this happened, because it would be a Big Deal. Even so, in the past Microsoft has purchased publishing rights. I’d suggest that it’s still an ok option if they were willing to buy those rights back. Starbreeze itself has a market cap of 74 million US dollars, so it’s really not a stretch to buy that, but the publishing deal would be tens of millions on top of that in all likelihood, assuming Koch was willing to sell them at all.