One question you might explore is what kind of experience do you want your players to have? What type of emotions do you want them to experience? Why might the various decisions be difficult/interesting?
A game with a high quality pre-scripted narrative might benefit from standard plot devices that justify why the characters do the things they do. But in an open-ended game world which your game seems to be, the player experience, not the in-game character experience, is the ultimate reason why the players will stick with the game. It certainly helps if the player experience and the in-game character experience match up. But just stating that the in-game character is attempting to rise to power, or seek revenge, or get rich, or whatever else, usually isn't enough if the game mechanics aren't sufficient to make the player have a similar experience.
So you might consider if you want players to often feel a strong degree of suspicion toward others. Or do you want team dynamics to arise, with players banding together as groups competing with each other? Is it okay if real-life friends can have zero suspicion of each other in the game and can band together safely against others, or do you want the game mechanics to even make real-life trusted friends a concern within the bounds of the game world?
When a player loses, do you want even that situation to be emotionally satisfying to the player, due to the loss often occurring after a period of rising tension and uncertainty and culminating in an epic loss for some and win for others? That can make for some great story-telling opportunities for players, and helps make the experience much more memorable.
Do you want players to experience the thrill and uncertainty of gaining power within an ever-expanding web of complications and instability? Or would you prefer that they have a relatively stable experience of always improving their situation within the game, with the rate of their improvement dependent upon how often they play, how well they play, and certain elements of chance or unpredictable opponent behavior?
These and other similar questions might help you figure out what type of game mechanics you need in order to make players want to keep playing.