Moon Diver is stuck inside its own design, trying desperately to escape the confines built around it, and never quite finding that exit. Kouichi Yotsui, credited as designer here, gave us Strider under the Capcom banner years ago, and brings a few philosophies from there with him, namely the platform hack 'n slash.
Strider was an aggressive design though, and that's what Moon Diver wants to be. Quickly repetitious and abrasive music blares in the background, characters push forward with a purpose, and hundreds of mindless thugs with blades for arms fall off the face of the earth or explode. In theory, it's a winning scenario.
However, you have to work for Moon Diver to come together. The very basics are hidden behind a leveling up wall, meaning that everything this is designed around takes grinding, replaying levels to fully achieve. Combos are crucial, not merely for the satisfaction of taking down rows upon rows of drones, but for the collision to work and in turn, keep the flow. Without them, you run through conveniently lined up antagonists, unleash hell, realize you missed half of them (because slashes only hit one thing at a time), and backtrack to clean up the remaining mess.
Even if combos were not a factor, Moon Diver could have survived like Strider, a single slash becoming something powerful, forceful, or even graceful. Instead, it's stunted and incomplete, a sense of power never really established. Jumping around gives the title a sense of agility, slides, double jumps, and ground pounds all quite fluid. The game wants you to push forth so badly, it shoves the ability to duck onto the trigger, as if "down" suddenly became a dirty word.
Level design matches the generous jumps, bringing in concepts more familiar to fans of the Super NES classic Run Saber, Moon Diver rarely is on stable ground. Levels arch, turn sideways, go vertical, or become so angular it becomes difficult to know which way is up. When it's moving full bore, ignoring the combat snafus, this is a beautiful thing in motion... and then it all stops. Yotsui and his team took it upon themselves to arbitrarily kill the flowing action and confine it to single rooms, enemies pouring in like they're from a different genre, and stopping the gameplay cold.