Crusader Kings III will allow you to run various secret schemes with a brand new system. Not just giving you the ability to take out a rival but perhaps sway someone over to your side too.
In the latest developer diary, they talk about wanting a system like the Murder Plot from CKII but have it "slightly easier to predict while keeping it unreliable in its outcome" so that murder is still an option but not quite as safe as before. It also sounds like it's been both expanded and streamlined at the same time, to give you more options for scheming while also needing to send out less agents.
Paradox are saying this scheme system will allow you to attempt murder, seduction and sway people over to your side to then possibly carry out a murder for you—oh my. You will need to be careful when scheming though, as it also has a Secrets and Hooks system. So if you murder someone, that's now going to be a Secret hanging over you that others can find out and use to Hook you into doing something for them. All of that you can do against others as well of course, by sending out a spy to get some dirty details on your rivals to engage in some blackmail against them. Sounds like the Schemes system is going to be a lot of fun to play with.
You can also get a quick video roundup of previous Crusader Kings III developer diaries in their new monthly recap video below:
You can wishlist/follow Crusader Kings III on Steam. It's confirmed to be coming to Linux when it releases next year. Everything I'm hearing about it so far sounds great, might actually get me properly interested in it.
As an additional reminder, the previous game Crusader Kings II is free to play on Steam.