This game is not an MMO. It is meant to be played solo or coop, in small groups, and best played with the group all starting at same time because there is a "world progression" on each map...

As the player (or group) progresses through the game, certain RAID events get added to a pool of possible events where groups of game mobs attack your base. and the game "rolls" for that possibility roughly every 50ish minutes.

What this means is, as an example, a group has progressed and killed the first 3-4 bosses on the world and has had those subsequent "raids" added to the increasing- pool of possible "hourly" raids.... New random guy suddenly enters that world and wants to settle in and try to play and survive, however, because the world has already progressed, that new player is also subject to the same "raid pool", in which that player has ZERO chance of surviving... because the ONLY way to end a raid is to either kill everything that comes to attack, or simply stay within the "raid arena" outline for 2 minutes... If the player leaves the circle, the raid pauses until the player returns to the circle and completes the full 2 minutes.

The exact OPPOSITE can also be true and equally as bad... say there is a small group and they are playing nice and slow, and then say some random shows up and starts defeating bosses on that map... it ends up ruining the progression for the original group and also puts them all at risk for the "impossible" raids because someone unlocked things way beyond everyone else's ability.