Note: Keyboard settings can be changed via the settings menu.

Default settings:
Up, Left, Down, and Right = A, W, S, D
Primary Fire = Hold mouse button down
Secondary Fire (when available) = Space
Pause and Menu = P

Similar to BT1, you must travel through giant bubbles, destroying enemy tanks and taking their bubbles to fuel your growth. As you grow, you constantly evolve and get ever better weapons. In the end, you'll have to face the ultimate adversary and defeat it to win the game.