The game's system revolves around the so-called Kakusei mode, and is one of CAVE's most complex. In Espgaluda, apart from the standard power-up and life items, there are two kinds of items to collect: green gems (which are officially called Seireiseki), and Gold Ingots. Green gems can only be acquired when you are in normal mode ( i.e. not Kakusei). When destroying an enemy in normal mode these gems appear and are automatically collected by your character.
By hitting the second button you switch to Kakusei. While in that mode, the enemies, their bullets, as well as the scrolling speed of the game itself, slow down to a crawl, while the player's speed remains unaffected. This effectively allows you to dance around thick bullet patterns with ease, and is the main reason for the game's accessibility.
Now the second kind of collectable items, the Gold Ingots, are mainly acquired in Kakusei mode. If you destroy an enemy in that mode, all their bullets turn into Gold Ingots and are automatically collected. So what you must do is let the enemies spread a lot of bullets while you whittle down their strength, and then, just when they are about to explode, switch to Kakusei mode, blow them up, and collect the Gold Ingots. The more bullets on-screen when you destroy enemies in Kakusei, the higher your score multiplier, up to a maximum of 100 -- hence the game's scoring gimmick.
However, you can't just stay in Kakusei forever, since while in that mode the number of green gems in your possession starts to decrease alarmingly fast. If you run out of gems bad things start happening: the enemy bullets will turn red and suddenly start raining down on you at impossibly fast speeds. This mode is called Kakusei Overmode, and should be avoided as it quickly results in death -- regardless of how experienced you might be.
Finally, just as in Esprade, by pressing and holding the third button a green barrier is created around the character, making him (or her) invincible, which subsequently turns into a laser when you release the button. The longer the button is held, the bigger the barrier, and the more powerful the lasers that will be shot. In Kakusei mode you can still use the guard barrier but there is also an auto-barrier enabled, presumably to help you out in tough spots. This means that the guard barrier is automatically activated if you get hit by a bullet or collide with an enemy.
The system might seem complex at first, and, well, it is, but it allows for great flexibility. You can milk the Kakusei mode to make the game easier; you can hone your technique to maximize the Gold Ingots (and therefore, your score); or you can do what I do and play the whole game in Kakusei Overmode -- impossibly difficult but also very exciting. Regardless, going for a high score is a lot of fun and extremely rewarding. It requires much practice, very good timing, and also some memorization, because you need to know when each enemy is about to die.
Bron:
http://www.world-of-arcades.net/Cave/Es ... galuda.htm