Just a note that this might be too much for the game but I just want to express my idea.
So once a month for a week, certain worlds will have the chance of 5-10 computer Ai “raiders” to spawn (the computer AI that controls the monsters too) and they are pretty tough. Once there is a notification that says they are coming, the whole world will make it as if it is a battle lock (only the people can hit the raiders not each other). If a raider kills you, you will come back, only you can not fight them anymore. If people manage to kill the raiders within the time period ( 1 minute) they get the chance to obtain items that were used by the raiders. Also on specific months, the raiders can change their appearance. Like for example it is December, they can wear christmas outfits.
Edit: The worlds they can spawn in will change all the time.
I might make a pixel art showcasing the designs of the raiders too.
Why not a item like a gallahorn or smth that calls for one raid? that would be cool. Or a dynamic world and you build a castle to defend against raiders until you die or a target is taken. Dang! you could even add towers and make tower defence in PW.
If it is just a dynamic world, it is just one world (im not talking about the servers). Raiders in the olden times raided many places so I want to keep that fact about them and make it into pixel worlds by random worlds being raided. As for that tower defence, im thinking of something with that, but, pretty good idea