The difficulty spike that ends most TD runs

Nearly every tower defence game has a wall — a wave where everything you built suddenly isn't enough. It's usually not bad luck. It's the game checking whether you upgraded or just kept building.

Fewer, stronger towers almost always beat a crowd of weak ones once armour and speed enemies show up. Upgrades scale better than a wider spread because they stack range and damage in your best positions.

I lost the same mid-game wave five times before I tore down half my towers and poured everything into three upgraded ones. Cleared it with resources to spare.

So when you hit a wall, resist the urge to add more. Ask which of your existing towers is doing the most and feed it. That mindset shift fixes most stalled runs.