To play strategically, select the overhead viewpoint.
The secret to staying alive in this game is to keep moving, firing at
the robotrons on your trail and at the occasional robotrons in your path.
Alternate your shots as you move by rolling your fingers on the keys and
combining two directions to create diagonals rather than searching for
the diagonal shooting key with your finger.
Save your game every time you progress a level, but be careful not to
overwrite a game that has more remaining lives than the one you're saving.