First Game ... advice needed.

Hi,
I've incorporated the suggestions everyone gave me into my first game.
They were all good ideas and worked well. Thanks for all the input!
I now have a simple game that gave me hours of enjoyment (and frustration).
Where do I go from here?

Changes suggested and implemented:

Title screen improved (animation and color rotation).
Correct alien in group flashes and then dies when shot.
Alien projectile drops from lowest row of surviving aliens.
True identity of alien projectile is not revealed until bottom band.
Alien projectile transforms into either a fuel pod or a bomb in bottom band.
Dropping bomb makes a bomb dropping sound.
Three alien speeds per level slow, stepping, fast.
Four different enemy patterns as level increases.
Fuel gauge with low fuel warning sound and FUEL LEVEL warning message.
CATCH FUEL message synchronized with fuel pod drop.
Bomb/Fuel pod impact sound and ground flash for bombs.
Missile and Alien projectile collision pushes projectile upwards and increases score.
Alien row is shielded and appears as an "S" after being hit until another alien row is hit.

Thanks,
Dave