A Death Note simulator. You start in a randomised country, pick your multiple choice background LCS style, and then you get the notebook. You would have a limited amount of time in a day to use the notebook, cause you need to eat/sleep/interact with people to avoid raising suspicion/etc. Once you are done taking care of your daily life from a Sims isometric perspective, you'd switch to a Shadow President style global map, where you'd have access to all the publicly known names and faces of people in the world, along with their publicly available backgrounds/crimes/and other info, so you can decide who you want to judge.
Wanna take out all of the Facebook users of the world? That's simple, the game supplies you with information of those people based on that criteria. If the criteria you want is criminals, then you'd need to find a way into various criminal databases, which may be helped or hindered depending on your character's background, and which you can do something about from your daily life mode. Every randomly generated individual in this game would be connected, allowing you to make them do simple commands before their death, mostly related to killing others ( e.g. John commits suicide at 10:43 EST, kills sister Jane in the process ), making them cooperate with you, turn against someone, etc. Each individual would be limited by circumstance, meaning you can't make a janitor launch a country's nukes, or make a child go on a killing spree. They may try, it's just not going to help you.
Eventually, you'd be targeted by L. L's name would be randomly generated each time you play, so you can't simply write down his name because you learned about in your last playthrough. He would use all the information on the planet, which he more or less has access to, to narrow you down to country, city and town of origin. L would try to befriend you as in canon, stay at a distance, do whatever, the only consistent thing being he will never give up even if you've managed to terrify the rest of the world. On the whole, you will be hunted by other organizations as well, but L's true anonymity makes him the only person in the game capable of standing against you till the very end.
Would make for some interesting AARs.