When a race is on the brink on being wiped out for whatever reason, they may surrender to another civilization. This gives all of their planets to the other race, along with whatever planetary improvements may be on them.
If a player surrenders to any A.I. race, the game will end in their defeat on the next turn.
The Hall of Empathy improvement, only available to Good races, doubles the odds that civilizations will surrender to the player with the improvement whenever they decide to surrender.
Surrendering can be disabled in the match setup menu.