X4: Foundations' massive diplomacy update adds an actual embassy room to your HQ, where you can entreat with aliens from across the galaxy and establish yourself as space Machiavelli

While not as flashy as Star Citizen or as popular as No Man's Sky, X4: Foundations is one of the most comprehensive space sims you can play today. Representing a return to form after the failed experiment that was X: Rebirth, X4 continues the series tradition of offering a preposterously detailed simulation of space—featuring trading, combat, space exploration, and dynamic faction politics—while also letting players build and expand their own interstellar empire.

X4 can be a hugely rewarding experience, provided you can handle its vertiginous learning curve and millions of menus. The space sim has quietly trundled along with a small but dedicated community for years now. But its latest update caught my eye. Patch 8.00 introduces a detailed diplomacy system to the sequel, letting you liaise with the universe's many alien factions, mess with inter-faction relationships to your advantage, and conduct daring espionage operations, essentially adding a slice of Crusader Kings to your adventures through the void.

Described as a "deeply integrated new gameplay feature" by developer Egosoft, X4's diplomacy system is built around three key components. At its heart is the embassy room, where ambassadors from across the galaxy gather to entreat with you around an actual round table.

The embassy room can be unlocked and constructed at your player headquarters. Once unlocked, you can invite other factions to send representatives to your embassy, though you can only do this if you have a friendly (or better) relationship with that faction. I like this physical representation of something that could easily be confined to a menu, though it seems these representatives function mainly as a quick access to the relevant faction menu, so it isn't quite as simple as it appears.

As well as interacting with factions directly, you can also manipulate them behind their backs through espionage. The diplomacy update introduces agents, recruitable NPCs who can serve both as negotiators and spies. Agents can be given their own ship and dispatched on a variety of missions, including spying on enemy ships, stealing valuable blueprints from other factions, and initiating "diplomatic interference".

What is diplomatic interference? Well, it lets you trigger diplomatic incidents and then influence them to your advantage, altering relationships between factions and improving your own position as a result. Depending on the current standing between the relevant factions, you can wade into trade disputes, arbitrate peace talks, manage territorial claims, and deal with cyber attacks and accusations of espionage. The results of your interference may result in changes to resource claims, redrawn borders, altered alliances, and even wars.

Egosoft describes diplomatic interference as "the most game changing element" of the update. "Changes in faction relations can have an extraordinary impact on the galaxy, as alliances, trade partners and supply chains shift." The big question, of course, is how well all this works with the rest of X4's voluminous network of systems. Recent Steam reviews are slightly less positive than the overall rating (76% versus 78%). But they don't say much about the diplomacy system one way or the other. At least nobody is complaining, I suppose.

The diplomacy update is available now. The free update coincides with the release of X4's Envoy Pack. This paid DLC introduces a "stealth-ready" frigate perfect for spies and sneaky negotiators, as well as a new mission chain, a new game-start that throws you right into that storyline, and an extra space sector. The Envoy Pack is available for $8 (£7).