Seems that the Hell difficulty is sort of like the actual arcade difficulty that the game can be completed in the difficulty lower than that but that is not going to count when comparing to the arcade version. We may be glad if you happen to complete the arcade version of the game but that's not enough. You have to be really good at this game genre if you want to face and defeat the true last boss to prove yourself an expert. For me, even with tons of experience in this genre, I'm still not an expert in it although I might have 1CC'ed certain shmup games.
There may be enhancements you can buy from as IAPs that will make the ship more powerful but then, it may seem to be unnecessary when comparing to the arcade version.
Strange thing is that the resolution of the IGS PGM is much wider than 320X224 standard resolution that only the HUD is pixel perfect. Other than that, everything is completely stretched like pixelated. But when played on the standard arcade CRT monitor, you can see that the HUD is squashed.
