Pilot Kids is a third party game for SEGA's famous and beloved Model 2 arcade hardware, from Psikyo. Though it's a shooting game, as you'd expect of Psikyo, it's pretty different to most of Psikyo's shooters, in terms of both looks and mechanics. On both fronts, I'd say the Psikyo game it's closest to is their weird Space Invaders parody Space Bomber, with it's quirky looks and multi-kill based scoring system.
It's a horizontal shooter, about two kids who get shrunk down, and fly toy planes to fight off all the other toys, insects and other assorted household objects that have come to life in a hostile manner. The players have two weapons at their disposal: a normal machine gun and lock-on homing missiles. The machine gun is almost useless as an offensive weapon, though it does have the useful property of being able to destroy the orange bullets the enemies fire (which, for the first few stages, is all they fire. Towards the end of stage 4, indestructable blue bullets will also find their way into the enemy's patterns). The missiles, then, are your main method of attack, and they're slightly more complicated than most hoing weapons.
Pressing the second button fires a marker, and the player can mark three to six enemies at once (depending on how many power-ups you have). Pressing the main fire button when at least one enemy is marked fires a missile that'll pass through any marked enemies, as well as any others in its way. The missiles are also the key to the scoring system. The first enemy killed by a missile will award double points, the next quadruple, and so on, up to a multiplier of sixty-four.
Though it's not up there with the likes of Cave's games, or even Psikyo's best, Pilot Kids is pretty fun, and has a nice selection of gimmicks. If it had ever got a sequel that refined things a bit and had slightly more exciting stages, such a game would probably be a classic.
There is also an additional mystery connected to this game, though: after a game ends, and you've inputted your initials, there's a counter that starts at a billion points, and depletes by however many points you scored. It keeps track of this every time you play, and I've managed to hack away a little over twenty million points so far. I have no idea what happens when the counter reaches zero, and apparently, no-one else on the internet has tried to find out, either.