An enemy AI player who failed to secure territory in the earlygame and was thus doomed to wander the earth as homeless vagabonds continues to benefit from the Neolithic Era respawn mechanic, assumedly because they never managed to settle a capital. In further detail I ransacked this AI's outposts back in the Neolithic thinking they were Independents/barbarians and he never managed to recover from it, despite most of the northern continent near his spawn being empty of other empires including myself for a good 50 turns or so, eventually I got tired of seeing his scouts lingering around and decided to kill him off as I had the other AI on my home continent, only to find out that I cannot kill him - his last scout will endlessly respawn even though he is now in the Classical Era (thanks to the competitive era stars?).