The greatest challenges.
Developed by Williams (Stargate by VidKidz)
Designed by Eugene Jarvis
The Winner's Book of Video Games describes a tactic, similar to the hunting strategy in Asteroids, involving a place on Defender's planet's surface colloquially called the "International Date Line." While the scrolling planet wraps around horizontally, internally the game still marks player and enemy positions using X and Y coordinates, and simple greater-than comparisons are used to do direction checks to figure out how enemies should chase the player. The International Date Line corresponds to the zero on the X axis of the game's coordinate system. When the player crosses over that point, he may have moved only a pixel on the screen, but his position is suddenly clear across the map, and aggressive enemies will rush away from the player to attack by going around the world. The IDL is near the tallest mountain on the planet.
The end of the world, which happens if you lose all the humanoids. It's survivable, but only just.
You're a spaceship, flying around a cylindrical world. Also flying around are enemies. Some of them try to kill you, but the most important ones, the green Landers, are more interested in roaming around looking for the humanoids scattered along the ground. This is why the scanner is important: the humanoids are all over the place, and the player needs to know where they are so he can zip there when one is being abducted.
If a Lander gets away with a humanoid, the two merge into a Mutant, an insanely aggressive enemy that not only comes zooming to your location but likes to approach from above your ship, where it's hard for your horizontal lasers to hit. If all ten humanoids are killed or abducted the planet blows up, and all the Landers turn into Mutants in every level until the next multiple of 5, when the player's humanoid supply is replenished. If this happens, you might as well walk away from the machine unless you're already a Defender wizard, because you aren't going to survive.
When a Lander makes away with a humanoid, there is a distinctive sound to alert the player to look at the scanner to see where it's happening. Often the abduction will be too far away to do much about it (after the first level the Landers get really fast when they're stealing someone away), but sometimes they'll be close enough to reach in time. To save the humanoid, you must shoot the Lander without hitting his victim dangling beneath him. If you shoot the humanoid instead, you won't have a Mutant to worry about, but you'll still be one guy closer to the end of the world. Better is to shoot the Lander, then grab the humanoid out of his fall.
Doing this is worth a fair number of points. I mention this because points are supremely important in Defender, because it's so hard that you are always losing ships. Even Landers can fire shots that can cover the length of the screen in a split second, and there are plenty of harder enemies than that. The only way to overcome the constant loss of lives is to earn them, at 10,000 points each, faster than you lose them. There is a hyperspace button that teleports the player to a random spot on the planet, but it sometimes kills the player just because he used it. And there is the smart bomb, which clears the screen of enemies but is in short supply, and the game is so loaded with things to watch that many beginners forget they even have them.
When I read bloggers talk about bullet patterns and end bosses, I can only sympathize so much, because I know Defender was ultra hard in a completely organic and random way long before this new-fangled kind of shooter, and yet also required far more than memorization and reflexes. Defender and Stargate are a particularly awesome kind of hard, a fun-while-it-lasts hard, where most players aren't expected to survive long but can get better with practice. Anyone can make an arbitrarily hard game, but to make it so hard yet compelling enough to try again and again, only genius can create this.
How hard is it?
Defender is, quite possibly, the hardest significant game there is, and yet it was a huge hit in its time. That combination of qualities, massively difficult yet tremendously popular, seems unthinkable today, but if it happened once, it could happen again.
If your game is genuinely fun to play for its own sake, then difficulty is an aid, not a drawback. Defender was so enjoyable at the time that players were driven to earn tremendous scores despite the difficulty.
An emissary from Computer-Land has come to test the limit of human reflexes. His purpose? Destruction.
Developed and designed by Larry Kaplan
The game gets faster all right, but it also slows down a bit when you lose a life. Yet while the player may survive for a little longer temporarily, the game has gotten harder permanently, because water buckets are taken from the bottom first. So, losing just one life usually means the end of the game.
The smile on the Mad Bomber's face when you lose. That bastard! It's said that, if you reach 10,000 points, he stops smiling when you miss a bomb. Sure, like we're going to get that far.
Kaboom! is an extremely pure form of game, so pure that it is actually possible to think it doesn't qualify to be called one. There are no pickups or enemies, but around the time of its release that wasn't really that unexpected. There is also no strategy, nothing to shoot at, no change of scenery. It is game boiled away; flavoring elements and impurities have turned to steam and escaped the flask. That powder left at the bottom is pure adrenaline.
At the top of the screen is the Mad Bomber. At the bottom there are your three buckets of water. The Bomber moves left and right, dropping a steady stream of bombs. The paddle moves the buckets left and right as well. Your job is to catch every bomb, matching the Bomber's movements.
As the game continues, the Bomber's bombs drop faster and faster. And faster. His movements become quicker and more erratic. If you miss even one bomb, they all explode and you lose a bucket. Lose three and the game's over. While the bombs slow down for a while after a miss, the game also gets subtly harder in that the buckets you lose are removed from the bottom first, decreasing the time you have to react to the Bomber's movements.
It is not exaggerating to say that there are WarioWare minigames that have more depth than Kaboom! has. But for what it is, that's okay. Kaboom! is about testing the limits of your reactions and nothing else. It is minimalist enough to qualify as a scientific experiment. Your score is a objective measure of the speed and accuracy of your reflexes.
That is all there is to say about Kaboom!, yet I can't recommend it enough in small doses. It's not just for breakfast anymore.
How hard is it?
As more a measure of reaction speed as a game, naturally it gets to the point where few human beings can keep up.
The game is more a test than a game, and the purpose of a test is to challenge. The point of Kaboom! isn't to have fun so much as measure your skill. Few games are this pure anymore. There is no strategy to Kaboom!, no tactics to learn. If you're better at using the paddle to match the bomber, the higher your score will be. Skill measuring games are rarely seen anymore, but still exist. The WarioWare games, at their core, are of the same kind as Kaboom!.
GameFAQ's page on the game (yes, there is one).