Well, to be honest, I don’t want to influence the game too much so I’ve held back from adding further input.
It’s vital that you are able to make further progress with a clear vision of how you want the game to proceed.
With that understood, I want to add a disclaimer - You are free to use or disregard the advice below because it’s going to be how I would do it but may not be necessary how YOU would do it!
First, let’s address the issue of the emotional connection of the Father being assassinated. It doesn’t work! There is no strong emotional reaction! Why? Because I, as a reader, with my outside perspective - Having started the game, the death happens on the second page!
Where do I get the time to build this emotional connection with the Father? I don’t! So, I think “Oh, ok. My characters’ Father is dead. Let’s see what happens next.” and not “Oh dear, this is sad. How will I avenge him?”
So while you may feel that actually, the Player should have an invested emotional connection - What you have is too distant for us to be involved in.
This brings us to an issue. I quite like the opening you start with which is in essence ‘in media res’.
We are getting directly to the core conflict of the story. That’s good! Better than good. It’s an excellent opener, don’t have any doubt about it.
But how I would do it? I would take the story all the way back to when the character was a child and/or a teenager.
Let us experience the life of a Roman family. Let us build this connection to the Father through a variety of activities.
For example - the Father might have taken you fishing or maybe to the colosseum/amphitheatre or even introduced his child to his buddies at the senate. Whatever you want!
Let’s call this the ‘prologue’ or in other words - the Character Generation section.
After that is completed then you could begin Chapter 1(which would be what you have now) and go into further details regarding the assassination.
At that point, it’s highly likely that the Player would’ve developed this emotional connection to the Father and therefore his assassination will hit all the emotional frequencies you wanted!
It’s as simple as that.