Don't buy anything in the beggining, just save up to 4 Homings, then everything will be a piece of cake for at least 15 levels. When you have enough money, buy Energy Homers too. Lightning is great too.
You can just skip Energy Homers and Lightning, and just save up for the Duck, but Energy and Lightning can be good to have.
Also, a great combo for the Bacteriazilla boss is Duck, Energy Homers and Laser Lock. They all have auto aim, so you can just focus on not getting hit.
Wow! Amazing gameplay, man! I really felt like I was the captain of Rymdskeppet, it's a huge feeling! Great job!
I got about 40k before I died, I'm pretty proud of that score. But it was quite sad that all those people on the Rymdskeppet died such a tragic death. :/