i like the idea and i agree with u it has a bad balance in increasing price of energy, and increasing enemys, and and the pilots of rainbow shielded ships xD and "spawn-over-player" issues...
you should have more than 3 lives
also
There needs to be a way to repair the damage done to your ship inbetween stages, it’s sucky having to try to navigate a stage with only 1 hp left from the previous sage.
but is a good game