This is a delicate balancing-act, which Raiden III performs wonderfully and in a way that contrasts to most of its recent rivals. In these other contemporary examples of the vertical shoot 'em up - Dodonpachi Dai-Ou-Jou, Ibara, Mushihime-sama etc - enemies spray curtains of random or patterned fire down the screen in an effort to overwhelm and suffocate the player's tiny ship with sheer volume of danger. This approach requires precision play, accurate timing and a steady hand on the part of the player but is often so visually overpowering that it leaves novices wondering if there's any point in even trying.
The Raiden series, by contrast, sends just a few assassin tanks, planes, warships and turrets across your path. They fire sparingly but, crucially, rather than spraying bullets randomly across the screen, they fire directly on your position. Now the challenge appears far simpler to the casual observer but, as each of your three types of weapon can only spray randomly back, the challenge is just as great - simply better disguised. What's immediately surprising with Raiden III is just how often you'll lose a life to a single enemy ship whose well-aimed shot you saw coming a mile off but somehow misread. Your ship has slow movement across the screen and so committing to your chosen route through the maze of enemy fire become of paramount importance - going back on yourself is often suicide.
Raiden III's sparse and methodical orthodox approach (as oppose to the fashionable and manic, bullet hell method) across its seven levels informs its whole design. There are some welcome amendments to the series' formula - every weapon comes with auto-fire as standard now and power-ups are kept if you choose to switch weapons mid-way through a level (previously you had to start off again from the weakest iteration). However, there are no complex scoring mechanics - you're rewarded for taking out an enemy ship quickly (up to double the default score per enemy) and there are no gimmicks requiring you to graze bullets or such-like for high-scores (although there is a 'Double' mode where you control two ships by yourself youtube Ikaruga-style). Visually, while the 3D graphics are bright, and the effects responsively vibrant, the environments and enemies are low-textured and are designs we've seen a hundred times before. Likewise the boss encounters lack the imagination of, for example, Treasure's output, failing even to match some of the inventiveness shown in the earlier Raiden games.
But despite these slight shortfalls Raiden III succeeds in being immediate and compulsive playing. It constantly betrays its arcade roots (for example, your score is reset to zero if you use a continue, forcing players to only use one credit when aiming for high-scores). From the aspect ratio (in the arcade the game is vertically aligned meaning, unless you're willing to put your TV on its side - and there is an option - you'll be playing with sizeable borders) to the functional and repetitive play options (Score Attack, Boss Rush and an art gallery) the game's heritage is clear.
Indeed, in many ways, Raiden III's release onto the Playstation 2 only really makes sense within a gaming landscape in which arcades still play an integral part. It's primarily meant to be a way for arcade players to practice at home in order to get good and then go back out into the wild to show off their skill in front of contemporaries (or wide-eyed gaijin). Which makes the game perfect for Hiro from Shinjuku but a little incongruous for Harry from the Cotswolds; the opposite of where a Eurogamer is used to being.
Without this competitive infrastructure surrounding Raiden III (other than the game's internal high-score table) some of the game's appeal and function is undeniably lost. But it's testament to the strength of that design blueprint Seibu Kaihatsu laid down seventeen years ago with the first title, that, even without all of that paraphernalia, this third game is still violently addictive. The only shame is that, when you finally manage to master the game with a single credit (and we're getting close), the only person around to show off in front of is probably a bewildered friend who's just popped round for a friendly game of Pro Evo.