You never move. Your artillery fires itself, and between rounds you dig through 180 upgrades to make it stronger. Beat the 25-round campaign, or survive as long as you can in Endless mode.
You never move. Your artillery fires itself while the enemies walk towards you.
25 rounds, 5 bosses, 10 difficulty tiers. Beat it, then beat it on a harder tier.
One life, no retries, a card draft every level, and no ending.