Keep the things crawling in from the edges away from the base. You move. Your weapon handles the rest.
WASD, arrow keys, or the touch stick move. The universal Pause button handles pausing. Pick one upgrade after every wave.
Choose one upgrade. Press 1, 2, or 3, or click a card.
Every enemy type is now active. From here on, each upgrade you take also pushes the swarm to send more bodies at the Centerhold.
You survived 0 waves.