“I believe Planet will talk to us if we are willing to listen. These fungal stalks behave as multistate relays: taken together, the neural net connectivity must be staggering. Can a planet be said to have achieved sentience?”
— Lady Deirdre Skye, Arguments in Council
This quote is probably the most important one in the game. It establishes with certainty what had previously only been mysteriously hinted at: Planet is alive. And not in a metaphorical sense. Nor in an anthropomorphized-for-simplicity complex-systems-analysis sort of way. It is quite literally a living, thinking being, albeit one that is necessarily profoundly alien to human experience.
And it turns out that that the fungus tiles that the player has been paving over to make way for farms and mines are actually little pieces of its massive world-brain. The analogy would be if a colony of dust mites flew up your nose and started tearing up little pieces of your brain to make cozy little mite-burrows. Chances are you wouldn’t appreciate it much.
In canon, this extremely surprising fact seems to be playing in favor of the Gaians. Which makes sense. With their religious devotion to ecological balance, they’re the ones who are the most ideologically predisposed toward recognizing what’s actually going on here on this alien world. And even then, it takes them a third of the tech tree and a substantial outpouring of mineral resources on secret projects to actually understand what they’re seeing.
Which brings up an interesting question. What, exactly, is the Xenoempathy Dome? What does it do? The video is just several shots of pink fungus set to soothing piano music, after all. It’s emotionally resonant – having empathy with the alien planet is calmer and more reassuring than you might think. Especially given the existence of mind worms. But it doesn’t do a lot to explain to the player what’s actually going on here.
In the gameplay, building the Xenoempathy Dome gives a few related effects. First, it allows all ground units to treat xenofungus squares as roads. This is really great because until now, fungus squares were more difficult to traverse than normal terrain. They would always consume a unit’s whole move to enter and sometimes, depending on the Planet rating of the faction, the move would just fail. With the Xenoempathy Dome, a unit’s movement speed is tripled and moves never fail. Essentially, every unit now moves through the fungus like the mind worms do.
Second, it doubles the rate by which formers can plant or remove fungus from the map. Before, it didn’t make a lot of sense to be able to plant fungus, as it was just a useless obstacle. But now, it’s almost as fast as building a road. Better, in fact, since rival factions’ units can use your roads but they can’t use your fungus highways.
And, finally, it gives a lifecycle (morale) bonus to any mind worm units artificially produced by the faction. Since psi combat is all morale-based, and thus independent of weapons or armor technology, this is a significant bonus for a faction that’s relying on psi attacks to make up the difference.
So, putting all that together with the quote and the required technology, I think that the Xenoempathy Dome is best interpreted as a souped-up Centauri Preserve. Building and operating it – presumably with lots of empaths in trance states listening to dreamlike piano music concordant with New-Age style – is what Lady Deirdre means when she urges her fellow Council members to be willing to listen to Planet. And the collection of benefits are coming from sub-rational conversations with Planet. The empaths make regular requests (like help me get through this fungal patch, or help grow some more fungus here) and the Planetmind can be made to acquiesce to these requests.
This is the sort of revelation that, in less artful hands, would be liable to shatter the typical player’s suspension of disbelief. It would be easy for this to come off as a cheap gimmick or a wild flight of fancy. But, like the best science-fiction authors, Reynolds has been setting up this technical mystery from the very first turn of the game. And he’s done enough of the legwork to know what sorts of intermediate questions he needs to get the player to ask before they’d be willing to take this leap. It really is brilliantly done.