Languages and Translation
Languages and Translation determines what diplomacy is even possible between two empires. At the start of every game, all factions begin entirely neutral towards every other faction — and unable to properly communicate with most of them.
Why Translation Matters
Every empire and race speaks its own language. Until one empire has translated another's, the two can barely exchange more than the most basic concepts — and diplomatic options between them are limited to just two: Declare War, worsening relations, or Offer Peace specifically to end a war and return to Neutral status, which uniquely requires no translation at all. Every other diplomatic action does require it — including using Offer Peace a second time, from Neutral to genuine Peace, which only works once the two empires understand each other. See Diplomatic Actions for the full detail on how the same action behaves differently depending on the treaty status it's starting from.
Open Communications
Open Communications is the diplomatic action that solves this. It's the one action explicitly available without translation already in place — fittingly, since its entire purpose is establishing it. Once complete, both empires gain full mutual translation, opening up every other diplomatic action between them from that point on.
See Diplomatic Actions for the full cost and time requirements of Open Communications, along with every other action that depends on it.
