Do not forget to buy the grenade gun until you finish level 7. There are no grenade guns at the next levels. It is almost impossile to complete blow-up-15-enemies mission at level 9 without it. Also it is a great help in killing boss with no more then 80 shots. And finally, sometimes, if you broke an elevator - you can help yourself with "rocket jump": just shot a grenade under yourself and jump simultaneously.
To get best ships - unlock Scraping Rod first. Then turn off autofire in options, start game in easy mode, take fast ship. After completing first level - buy Scraping Rod.
Now you can use any last boss to get 100x multiplier. Just shot down its extras and stop shooting. Then use following algorithm:
1. Shoot him once.
2. Move close to any bullet during next few seconds getting 1-3 multipliers.
3. Repeat, until you get 100x.
4. Kill the boss.
If any bullet hits you - you lose about half of your earned multipliers, so be careful.
Good luck!
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 "Frantic 2"){kind=icon}