If you have never played a COIN game (COunter INsurgency, a game system developed by Volko Ruhnke for a series of games published by GMT), but wonder if it is something you may enjoy, The Coin Tribes' Revolt: Boudica's Rebellion Against Rome is a good, inexpensive opportunity.
I fell in this category myself until recently, when I stumbled across a printed copy of the Tribes at the UKGE, and grabbed it to see if the quadripartite system appeals to me. I don't intend this post to be a review, so I will only mention some of my thoughts.
Each of the four factions in the game has a different agenda. The Romans and the Catuvellauni are allies but have a different winning condition each. Likewise, the Iceni can form temporary alliances with the Trinovantes but it is each faction for themselves in the end.
So you pitch them all four against each other, like a puppeteer. Or you choose to play as one of them yourself, and then check what each of the three bots does in their turn. Unlike other PnP games that serve a half baked idea as a 10 minute activity, this one packs a lot of decisions in its small box. There is an interesting initiative system that only allows two factions to act each turn. And when they act, you have to consider your choice carefully.
I ended up ignoring the bots and playing each faction to the best of my abilities. Here is the problem, though, and I understand that this is strictly personal. Even if I admire the smartness of the design, the theme doesn't do anything for me. I couldn't care less if the Trinovantes are victorious. Now, if this was an Andean Abyss reskin, I would speak differently. Make me a Colombian drug lord or a FARC rebel, and I can get into it. But in this setting, I can't be bothered to play an assymetrical game, because I'm not 'feeling' it.
If you are passionate about Roman history, by all means give this one a try. It is a very good game for its size and scope. If you want to see what a COIN game is like, try it as well. I am a theme person above all else, so my pocket is not the perfect fit for this COIN. It does have value nonetheless.