Silly Bombs and Space Invaders

[OscarW]

Fire up the silly bombs and save the friendly aliens! Attention; you have limited bombs in each level. Destroy cactuses, collect bonuses and use fewer bombs to get the best score! Use your mouse to aim and click to shoot.

http://www.flonga.com/play/silly-bombs-and-space-invaders.htm

Please use spoilers for hints and walkthroughs:
[spoiler=Title Here]Enter text here...[/spoiler]

Please do not post a video walkthrough for 7 days.