To get in the mood for this article, here's some music from Donkey Kong Country 2:
The first platform games were about trying not to die. Dying occurred frequently and your main goal was to get through all the levels. As time went on, there was more emphasis on finding secrets in the levels. This allowed platform games to have dual goals: 1) get to the end of the game and 2) find all the secrets.
A casual or younger player's goal might be to simply get to the end of a game. This doesn’t even require completing every level because of warp zones and non-linear map screens that allow you to skip levels. A more demanding gamer's goal is to uncover every secret the game has to offer. In Mario64, this means finding all 120 stars (only about 60 are needed to "win" the game.) In Donkey Kong Country 2, this means finding all 40 DK coins as well as finding all 102% of the bonus rooms. These dual goals allow a single game to appeal to a wide range of players.
What Is A Secret?
You could hide a secret in the game somewhere ridiculously obscure. You could put it in a random location that looks the same as any other, and make it nearly impossible to find because it's so obscure. This is not a good modern design sensibility though. The secrets I'm talking about here are carefully, intelligently placed and they're meant to be found.
Think of these secrets the same way a mystery author thinks about their plots. A mystery is not a zero-sum game of writer versus reader. The writer actually wants the reader to figure out the answer—just not too early. The answer has to be hidden well enough that there's a sense of accomplishment in finding it, but there have to be enough clues to make finding the answer possible. The answer, just like a secret in a platform game, isn't randomly created. It's carefully designed and hidden, and carefully pointed out by clues.
Donkey Kong Country 2
I think Donkey Kong Country 2 was the first to implement this concept so masterfully, and it remains one of the best examples even today. The game is fairly easy to "win" simply by completing all of its levels. Dying is somewhat frequent, but the difficulty is pretty low and free lives are plentiful. Even very young players should be able to get through the difficult parts through repetition. The real game, though, is to uncover all the secrets. Each of the 40 levels has one to three bonus rooms and a single "DK coin."
I think the DK coin is the greatest thing in platform games. It's a ridiculously large, shiny, spinning coin that somehow manages to be hidden on every level. There's something magical about finding that single, well-hidden secret on every level that just isn't the same as finding 5 Jingos (Banjo-Kazooie), 100 coins (Mario64), or any of the ten zillion tedious things on your shopping list in Donkey Kong64. And don’t get me started about blue coins in Mario Sunshine.
Donkey Kong Country 2 has a well-designed hierarchy of secrets. Each level has:
one super secret (the DK coin),
one to three other secrets you "have to" find (the bonus rooms),
and other, less important secret items (banana coins and free guy balloons).
At any time, the player can check how many total DK coins they have and the percentage of bonus rooms they've uncovered. They can also easily check if they've found the DK coin on any given level, and if they've found all the bonus rooms on a given level. All the while, the character Cranky Kong taunts the player by telling them how they have no hope of finding all the DK coins and bonus rooms. This gives the player a clear idea of their mission: to prove Cranky wrong.
Having a clear system to keep track of which secrets have been found is critical in this type of game. Knowing that there are 40 DK coins hidden out there somewhere in a huge world and that you've found 23 of them so far, simply isn't fun. It's daunting. If you want to feel daunted like that, try finding all 100 packages in the enormous, sprawling world of Grand Theft Auto 3. By contrast, it’s a fun challenge to know that somewhere in this one particular level that isn't even all that big, there's a tauntingly large, spinning, golden coin that you can find.
Unwritten Rules of DKC2
Part of the magic of DKC2 is the way all these secrets are hidden. The highest compliment I can give the game is to say that I felt every DK coin was placed by a single intelligence—by one person. As the game progressed, I came to know how he thought and what he'd be likely to do. In essence, the game felt not like an action game of me versus the computer, but a strategy game of me versus the designer.
In order to create this feeling, the game established and religiously followed a few unwritten rules. First, bananas (the common items littered everywhere on every level) are always helpful. If they spell out a letter or an arrow, it's always a genuine clue, never a trick. If a single banana is placed in some precarious, seemingly impossible to reach spot, it's always pointing to a secret. If a banana is over a pit, it always signifies that jumping in the pit will not kill you. In effect, the bananas themselves are a character—a sentience—trying to help you at all times. DKC1 did not follow this rule, and that resulted in much frustration and throwing of controllers. In that game, you had to mindlessly jump in every pit just in case one of them scrolled down to reveal a secret instead of killing you.
Another interesting unwritten rule is about running at full speed through dangerous levels. Anytime there's a series of obstacles that require timing to navigate (swinging vines surrounded by deadly bees, spinning cannon-like barrels over pits), you can always progress safely by running at full speed and taking every jump as soon as possible. Put your fears aside and have faith that jumping from vine to vine at full speed will somehow work out, and that you'll never touch a deadly bee.
What's the point of this? Most of the gameplay of this game is the act of looking for secrets. Running through levels at full speed isn't going to help you find any so there's really no "cheating" involved. It's just a convenient way to get to a particular part of a level if that's where you think the secret is. Again, the game is trying to help you, and stays true to its promise, never tricking you and never losing your trust.
You also learn a certain consistency to the methods of hiding secrets as you play, if you’re observant enough. The oldest trick in the book is that a big secret is often hidden just barely beyond a small one. It might look like the screen would scroll up a bit if you jumped to that cliff...and it does, revealing a not-so-valuable banana coin. You found the "secret" so time to move on, right? Well the all-valuable DK coin might be just a little bit higher if you noticed the smaller cliff above the one you're standing on.
The game also constantly tests the players assumption and first instincts. After 10 levels of starting on the left side of the screen and scrolling right to progress, it trains the player to assume all levels are this way, then sneaks in a level where the DK coin is mere inches to the left of the starting point, barely off-screen. Most players will never even realize going left was an option. And where is it "legal" to hide a DK coin? I'm sorry to ruin this secret, but I just can't resist. Spoiler alert to skip to the next paragraph, if you must. 39 of the DK coins are hidden somewhere inside a level. Exactly 1 DK coin is hidden in a bonus room inside a level. A secret within a secret. The game has trained the player to assume that no secrets would be in a bonus room, so what better place to hide something? This particular secret was very memorable to me because after I failed to find it several times, I put the controller down and simply thought about it where it could possibly be, then realized a certain bonus room on that level had something suspicious about it, and that it must be “legal” to hide DK coins there after all!
More subtly, the layout of levels often subconsciously suggests a certain path. Jumping from this ledge to that vine and so on just looks right. It feels like the right way to go. And as soon as you believe it's the right way to go, the game has got you. And that is the beauty of Donkey Kong Country 2: it's a constant psychological battle against your own assumptions. Every step of the way, the game is trying to fool you. The bananas are on your side, the but the rest of the level is not. Like a good mystery, there's always a clue—always some indication of where a secret is. There's a way to find every secret without having to constantly kill yourself by jumping into random pits like in Donkey Kong Country 1.
For a full spoiler, here's a video showing all 40 DK coins in DKC2:
Suspense and Secrets
In storytelling, suspense is a powerful technique, and also an economical one. If the author can create the credible threat that something bad will happen, they can then play with us through anticipation. All the moments where nothing happens seem excruciating because we keep thinking this could be the time something really does happen.
I say that's economical because it's a lot cheaper to keep us interested by action that only happens 5% of the time than 100%. And yet 100% of the time, we might be on the edge of our seats. One example is the torture scene in Reservoir Dogs. Before this scene, the film establishes Mr. Blonde as a person capable of violence. In the torture scene itself though, literally no torture is shown. The anticipation of it is nerve-wracking, and the only actual action that happens is very brief, and off camera.
There's a parallel to games that are about finding secrets. Even though the secrets might make up only 5% of the game, every little step might be a secret. Suddenly, the other 95% of the game is that much more engaging because every careless step you take just might be the one that bypasses the secret.
For a platform game like Donkey Kong Country 2, this means that running to the end of each level is the last thing the player wants to do. It takes only 1-3 minutes to run through any level of the game, but because the real challenge is to find secrets, not pass levels, there's much more gameplay. A player might spend 10 minutes on a 1 minute level, or even longer. Maybe much longer, and if done right it will feel fun, not tedious.
Think about how little of the game's art and programming assets were devoted to these secrets. The graphics for the DK coin, the bonus rooms, and the system of keeping track of which secrets have been found are all minuscule compared to the design of 40 levels filled with animating enemies. By designing levels around secrets—not sticking secrets into levels—this 5% of development effort made the difference between a C- game and an A+ game.