Swarmward

Enemies enter from the edge of the arena and move toward the center. Defenders occupy the ring around the core, so placement determines which paths and waves they can cover.

During a level, resources are spent on new defenders and upgrades. Four recurring defender roles handle direct damage, groups, control, and longer-range threats in different ways.

Each world contains eight levels. The fourth is a miniboss encounter and the eighth ends with a boss. Completing a campaign also opens its endless format.