It's clear to me that psychotropic drugs were widely available to the Namco programmers in the 90s. Holy crap is Pistol DNB a weird game. In fact, it is immediately going to be enshrined into the GOTD HOF for Weird games.
Underneath all the kook, it's just a good horz shooter. But it's wrapped in some of the crazier graphics and storyline you'll ever see. You are a little Japanese dude with a gun mounted on your head (don't know if that's a genetic condition). There is only one button. You shoot your headgun (a new term!) by pushing the button, but you also have a charged shot. If you hold down the button before you let it go, your gun charges up - you can see it bulging - and a bigger and more effective cannonball comes out. Interestingly, as it is charging, it also changes the gun/cannon's angle. So while your pistol shots are straight ahead as is normal, your cannon (charged) shots, are lofted at approx 45 degrees and then quickly head for the ground as gravity takes hold. Hopefully, you have a good eye for parabolic curves - as that's how you hit the enemy. The cannon shots are WAY more effective than the pistol, but you have to hit your enemy directly (unlike the bombs in other shmups).
Extremely difficult bosses haunt the end of each stage, but let me back up a minute. When you start the game, you see a grid of levels you can select from. You either choose the leftmost starter level, or choose the first stage from any of the 5 paths the game can take - each with its own enemies and graphical themes. I suggest the single starter level to the left to get your feet wet, the following levels can all be difficult to complete. Each stage is kind of mini. You battle some crazy-ass unrecognizable cartoony stuff and then quickly come to the boss. If you die, you start the stage over - no help in defeating the boss. At least the levels are short. Beat the boss, and it's on to the next stage. But it is terribly hard, I had to cheat to get to the third round after dying a gazillion times.
The most interesting aspect of the game is the utter craziness. The enemies are almost completely indescribable (except for the ninjas), the stuff you pick up is unrecognizable (although you can earn armor that helps absorb enemy hits), when you die, there is a quick graphic of you crying like a baby, naked - except for strategically placed Japanese fans. Just look at the pics here. It's fun nonsense. And of course, it's all in Japanese, so whatever explanations there are about what is going on are lost on me.
For you historians, there is a little controversy about the game, you can check out a video showing it here...