This is not about fighting zombies, but battling other players. Your shelter not even having normal features of a bunker, but stronger players just come, destroy all your troops and loot what you have gathered. Totally pay to win. With 10-50€ you can have the basics to survive, but you still having no chance to with a events or get nice boxes. Every new event adds more buyable features to the game. Sure, patience can get you stronger, therefore one star more. And the support is not helpful.