I'm stuck on the Stage 4. The best I could achieve was 50% of the last health bar of the boss, but that happened only a few times within dozens of retries. I was using machine gun and sword. I defeat the mini-boss first stage with sword, it's fast but I lose some HP there. The second stage of the mini-boss is not a problem for me. However, I find the final boss hard, as every hit I take results in severe damage, and I don't know how to attack & defence effectively there. Any advices on getting to boss with...

Might as well make this topic. But yes, do make sure any bugs that any of you find are placed here. Bonus points for being able to replicate the bugs and writing clearly (that helps us find them better).

So far I've only 'found' one, but apparently this game has ingrained cheat codes. I say 'codes' because I assume there's one to unlock all guns somewhere, but I haven't found it. Has anyone else stumbled on this game's codes? So far the only thing I've found is Konami Code=Invincibility....

Has anyone been able to unlock this achievement?

I ask cuz just... wow difficult much? Even on easy mode i have yet to beat the first stage and you have to do all this on 1 life?