Unlike, say, Gate of Thunder, Dead Moon isn't the sort of shooter that I can play and enjoy at any given time. Instead, it's a game that I'll power up only after spending a few years away from it. Once I do return to it, I inevitably find myself surprised at how enjoyable it is and proceed to soar through it three or four consecutive times. It's kind of sad, though, that once I wrap up those three or four trips, I always feel I've had my fill and can go three or four more years before giving the game another look.
DM has a lot going for it, including nice music (the intense melody that Scene 3 kicks off with is actually the sort of tune I'd expect to hear in a Castlevania game) and beautiful backdrops that feature stunning parallax. It also boasts a solid control scheme (aside from the requirement that the action be paused for ship-speed adjustments, but those aren't really necessary), post-stage play data, acceptable weapons that all come in handy, consistent pacing with hardly any dead space, and stage environments that connect up logically.
But there are two problems: the enemy armada is rather lame, largely consisting of nondescript "shapes," and there's nothing unique to speak of--no cool power-up system, no interesting theme, no memorable boss fights. The game's most distinct element is the automatic "about-face" that your ship performs when a boss decides to switch sides with it--not exactly the trump card you'd expect from an exceptional shooter.
Indeed, Dead Moon isn't exceptional. It's merely a good game that kinda lacks its own identity.
Here's a harsh contrast for you: the attractive multilayer backdrops and the all-too-basic enemy designs.
The skeletal bosses are a little more interesting than their "balls and blocks" henchmen, but fighting with fossils eventually gets a bit dull.
The midbosses are traditional pieces of machinery, the likes of which you can find in any ol' Gradius clone.
The weapons are serviceable. There's nothing at all original about green waves, red rings, and blue lasers, but at least here they look pretty cool and all have their useful moments.
Forget the "turning around during boss battles" stuff; the coolest thing about Dead Moon is that its levels connect up logically. For instance, your ship descends into a lake at the end of Scene 4, and then Scene 5, logically enough, takes place underwater. This might seem insignificant, but sensible level progression was often considered unnecessary in old-school-shooter game design.