Everything right about the game, and its completely ahistorical (yet glorious) anachronism stew, can be summed up in the image of Boudica invading the city of Rome on an armored war elephant.
Everything wrong about the game can be summed up in the fact that you're not playing as her but instead as the person who kills her for no good reason. Seriously, game-Boudica and game-protagonist had exactly the same enemies (and the same motivation) and mentioning that fact to Boudica probably could have avoided an unnecessary, prolonged, fight to the death. A fight before and during which there was plenty of time to mention that.
But ... Boudica on a fucking war elephant invading the city of Rome.
There needs to be a game that lives up to that idea and that image. The game could even be called, Boudica on a War Elephant because that's like naming a movie Fun and Explosions with Chiwetel Ejiofor; I'm sold on it, take my money.
As I wrote this post I began to realize that the sheer epic awesomeness of Boudica on a War Elephant can't really be captured in a single game, though.
Consider that the war elephant is clearly taken from Hannibal (at war with Rome from 218-201 BC) and the barbarians breaching Rome (so Boudica can be riding it through the streets trampling the soldiers in her way) is taken from Alaric's sack of the city (410 AD) meaning that that one image is pulling from over six hundred years of things that Romans fear.
No, Boudica on a war elephant cannot be told with threads of point of view that number so low as to fit into a single game. This calls for a damned tapestry.
One can see how one might divide things into games, the game/s that follows Boudica and her daughters would be the main game/s of the series, then we could lump side games in by ally. Carthaginians (Hannibal's people) get a game. Visigoths (Alaric's people) get a game. So on, so forth. Why not throw in Spartacus too?
The ninth legion was nearly obliterated with the only survivors being those who fled on horseback. A legion is composed almost entirely of people on foot. What if they weren't all killed? A game that follows a very angry, very abandoned-feeling centuria.
When London was evacuated it was under the offer of, "If you join my army, I'll help you get out of here safely." So women, old people, presumably children though the Roman historians are notably silent on this point, slaves, anyone else who isn't eligible for the army, and anyone who cares about any of the previous people, were all left to die.
Give the remnants of London a game where they're pissed off at the Romans in charge and thus have a common enemy with Boudica.
* * *
The game following Boudica herself would be the most complex because in addition to fighting on foot, on horse, and on elephant, she's also got to be doing coalition building, army leading, and stuff like this.
Real life Boudica was elected head of the coalition she led against Rome. It wasn't a position she inherited. In fact, she was never supposed to inherit a damn thing.
When her husband died her two daughters were supposed to inherit rule.
Prasutagus, her husband, was king of the Iceni and a Roman ally, but he knew that Rome had a habit of allying with kings, not nations/tribes/peoples/whatevers. Why? Kings die. So when the ally-king died Rome just took over the nation the king had ruled. He tried to partially avoid this fate by naming the Roman Emperor co-heir to the kingdom.
The idea being, "Yeah, fine, we're part of Rome now, but..." the daughters were also named co-heirs. Thus, "but these are the people who should take over local rule."
He thought that by doing this the Emperor would be overlord but his daughters would be underlords and then there could be a retention of local rule on matters not of imperial importance (most matters.) Or some such.
It didn't work. The empire ignored his will, seized the territory, enslaved the nobles, flogged Boudica, and had the daughters --the ones who were supposed to become rulers-- raped.
Boudica was quite naturally pissed the fuck off, but she didn't just ride off in a fury. She started coalition building and when the coalition was built she didn't automatically become the one in charge; there was an election.
That means it's very much not about birthright and inheritance, it's about, "We're all pissed off at these people for various reasons, and who do we think should lead us?"
Now, stepping away from real-life Boudica and looking at Boudica on a war elephant, she's obviously traveled widely (in time and space) and made allies with the various barbarian hordes who have all agreed to work together under her banner. Hannibal and Alaric work for Boudica. As I said, let's throw in Spartacus too. Anyone who scared the ever-loving fuck out of the Romans.
There's gameplay to be had in that. We can see Boudica on a war elephant's game as a mixture of politics, non-real-time strategy, real time strategy, and straight up combat. She needs to get people to join her, plan attacks (and probably defenses), and then adjust those plans while in the middle of combat. (Boudica was not a rear echelon mother fucker.)
It's a cross genre game
* * *
Now I don't particularly want to have rape in my anachronism stew (I prefer lighter fluffier slaughter-the-imperialists games) but I do want to visit the characters of Boudica's daughters who accompanied their mother into battle.
Since there were the two of them one possibility would be to have their game be heavily involved in them using a combat style that makes heavy use of having two allies in close sync with each other, though I do know that a lot of games that have tried the "We'll have two player characters at the same time," thing have utterly failed on that front.
It could start with them escaping before the Romans could do horrible things to them and continue as a melee game all the way through Boudica's epic victory at Rome.
* * *
The myth of Iphis is the story of a transmale character. In the myth Iphis is magically transformed into a cismale because the ability to make babies with one-true-love Ianthe is more important to Romans than the wonders of hot lesbian sex.
I bring this up only because it gives us a nice name and backstory for a Roman viewpoint character.
Our Iphis was born on Crete to a murderous asshole father, Ligdus, and a loving mother, Telethusa. The family could only afford to raise one child so the father, who wanted a son, planned to expose their firstborn if it was a girl. (Exposure being the traditional means of killing babies because their blood isn't technically on your hands since you killed via inaction rather than action.)
When Iphis is born Telethusa says, "It's a boy!" even though genitalia would seem to indicate otherwise. Of course she doesn't try to trick Iphis, but eventually Iphis realizes that he is in fact a boy and so, even after he's old enough to run away to sympathetic family/friends of Telethusa and live as a girl, Iphis keeps on being the boy he is.
Iphis and Ianthe meet and fall in love but they're both from extremely poor families so Iphis joins the army and ends up being shipped to the opposite end of the empire, eventually attaining the rank of centurion in the 9th legion.
Having Iphis be a centurion allows this game to utilize how Romans actually fought, which was as a unit. A prologue or training level could have Iphus' centuria (80 foot soldiers including Iphis himself and 2 riders who could serve as messengers or scouts*) fighting along side Iceni against some common enemy leading to a, "Wait what?" when things reach the point of trying to crush the Iceni.
As mentioned, historically the 9th legion lost all of its troops on foot. This is even though a legion is composed almost entirely of troops on foot.
There are two possible ways to justify Iphis' centuria suriviving. One, Iphis did something that merited being spared. (Maybe Iphis is the reason Boudica wasn't hauled off as a slave before she could start a rebellion.) The other is that they played dead/were merely knocked unconscious, and then snuck away before anyone took the time to verify that the Romans were all actually dead.
Either way, they see what happened as a betrayal, probably make revenge a first stop on their across the empire trek towards home. (Iphis is in love with Ianthe who is back in Crete, remember.) Whether revenge takes them to the cavalry that fled, abandoning them, or Catus Decianus, the person who should have sent more troops ahead of them so that the city they were there to save would have been extant and resisting the Boudica rather than destroyed and in her rear-view mirror doesn't really matter.
If vengeance, then traitor, which means that their primary enemies on this trek across the empire will be other Romans. Romans who try to punish them for vengeance, Romans who claim they're deserters for not regrouping with the cavalry who fled, Romans who want to conscript them to fight the ever growing barbarian threat as Boudica builds alliances and Rome is attacked from all sides.
Since all roads lead to Rome, the road to Crete leads through there, which could have them showing up just in time for Boudica on a war elephant.
Actually, that could be a deciding factor in them not going around. ("It's not like anyone will notice us with all this going on.")
* * *
Say that one of the cavalry people with Iphis' centuria didn't retreat, but instead stayed with them, and thus was separated from the 9th and had that same sense of betrayal.
The cavalry assigned to centuria weren't organized into any kind of groups (there were 120 of them and 60 centuria to legion, so the most there could be would be groups of two) which allows for a more traditional one person action game. (Anyone who is wondering, the cavalry who did fight as units, instead of being assigned to centuira, were those of the auxiliaries, not the legions)
So we'll say Cicero (name means "chickpea" but when his parents named him they probably were thinking "Great orator and savior of Rome") starts off with Iphis' group in that capacity but then goes his own way.
A way that shows yet another angle of the great and epic story of Boudica on a war elephant.
* * *
And the intertwining narratives go on. I don't know much about gender roles in non-Rome places. But from Rome places it seems like a good place to find an anti-Rome trans-female, genderfluid, or genderqueer player character would be London. Anyone who looked female at the time of the evacuation was told, basically, "Stay here and die, we've got shit to do and you don't factor in."
* * *
All roads lead to Rome, which is to say that the epic climax of the thing, which many of the characters would see their particular angle of in their game, is Boudica on a war elephant storming the city of Rome and taking down Nero.
After that things settle down a bit. Maybe Boudica becomes emperor while her daughters return to rule ... whatever portion of Britannia still wants to be under Iceni protection and thus rule. Or maybe not. There might not be much of an empire left to rule after the Goths get their food, Spartacus gets the slaves freed, and ... whatever the other enemies of Rome from various points in history wanted is granted them. Going back to the Iceni and leaving the Romans to try to survive on their own now that they don't have slaves and have been forced to keep their promises might seem like a better choice than taking over.
Hannibal, for his part, returns to Carthage a victor.
Wherever Boudica ends up, she totally takes a breeding population of war elephants with her.