This RPG is perfect for me.
Ahem, allow me to involve my experise here to flesh out the ideas.
The protagonist (the first assasin) is sent to kill the prince/princess of a set nation. The reason this is so is because the king, his/her father is very ill, and it close to time for him to pass, and the prince/princess with ascend the throne. The assasin's company (I don't have a name thought up, but Black Water sounds cool....Poisoning the royals politics) sends the protagonist to kill the heir to the throne, but he could be stopped by royal knights (if he's not stealthy) or he could merely have a change of heart standing over her bedside, about to kill her.
He returns to the comapny headquarters, and says that he wants out. The leader says that the only way out is through death, since he signed a blood pact. The assasin is asked if he would like his life, or if he wants to stick with his precious emotions and die. The assasin answers by running out of the room. The leader of the company smirks, and decides that he'll give the protagonist time to flee.....But, in the meantime, he'll have some fun.
The assasin returns to the castle, since last time he was unable to complete his mission. As he is thinking, the castle is besiged by ballista and catapults. The vastle walls are breached by hundreds of mercenary soldiers. The Royal Knights struggle to push them back, but the mercenaries are too large in number, and although the Royal Knights seal the gates, an assasin gets inside the castle.
The protagonist follows, and kills the assasin before he is able to kill the heir. The assasin asks the heir if they want to live, and they run to the throne room.
In the throne room, two mercenary soldiers appear, looking for royal treasure. The proagonist kills them, and they are about to flee, when a Royal Knight hears the fighting, and comes into the throne room. The Knight says that it is essential that the heir survives, and the three of them flee the castle together.
Several days pass, and the king is declared dead, and the royal knights are either killed or taken prisoner. The heir is upset by this, angry that they were unable to do anything to stop them. They ask who could do this, and the assasin explains his ties with the mercenaries that besieged the castle. The heir is at first upset, and hreatens to have him hanged at the gallows, but realizes that they hold no power here. The heir realizes that the only way to fix this is to get revenge.
I think I fleshed it out a bit more, and it explains their escape. But, it doesn't have to have only assasin elements--It can be a tactical war game, with each side predicting and reacting to the others moves, and each side is gambling their own lives.
Oh, and, I will join when this RPG is created.