[Kereth]

has numerous events with monsters attacking cities, though they only happen periodically, but they do result in players uniting to defend the land under attack. In the case of city raid events (goblin raiders, uruks, kizanki psionics purge, 9-foot killer kangaroos, etc), however, there's not much of a risk of actual loss (at least tactically. Players can, of course, easily be killed), as the various npcs don't actually attack each other, so the event just results in the area being swarmed by hostile monsters until the players can drive them out, but there are also numerous events where player castles come under threat, either from pests which attack the golems, thieves which try to steal their stuff, or armies of undead or gigantic monsters which threaten to damage the castles themselves. These latter events get a great deal of attention as well, especially because if they were ignored, player's valuables might be at stake, though the playerbase has become effecient over time at rallying to defend their own, so significant setbacks are almost unheard of. Other events include wildfires spreading across planets (which players must extinguish before they cause damage), blessings and curses upon various alignments, angels/demons/knights of balance/headless horseman/etc who attack the retroverse, either seeking to kill everyone or just those who are contrary to their alignment (newbies are, fortunately, protected from these events, and their are plenty of ways to take shelter), and many more. They typically run one event each day, though the timing varies, so unless you're logged in all day long, you won't necessarily see all of them run. Still, they're frequent enough to keep things interesting without interfering with normal gameplay too much.