Damned, skipped another update last week. Here’s my latest progress report. Level 4 is finished, and here’s a look at the action:

The fighters you see rotate in flight, and when the rotation suddenly speeds up, better get out of the way because it means you’re about to get pwned! The bomber is also still present, of course, and I really like the way it works. Also, you’ll notice there are two buildings on fire. The defense unit is far from perfect and often misses shots, so don’t just sit back and relax.
This means there are two more levels left. The two base units left are entirely passive, so I don’t have to waste much time on those. All I have to pay attention to are the remaining enemies. I hope I can finish this game before I’m dead.