This is a supertrope for any way that designers communicate things to players using level design. This is Show, Don't Tell style stuff, techniques you can use to inform players without having to bore them with text.
Often, instructive level design is about teaching the player controls, basic rules, or patterns in a game. E.g.: The first scene of Super Mario Bros. can teach you "Mario will be hurt by goombas, Mario can get things out of question blocks by hitting them from below, Mario can grow big by getting a mushroom, etc." Obviously you'll find that kind of instructive level design at the beginning of a game.
You can use instructive level design for things other than teaching basic rules, though. In Portal, for example, test chamber 10 (around half an hour into the game) teaches you the "fling" tactic. The "fling" is not a basic rule of the game, but is a useful tool that is constructed out of a combination of basic rules (the basic rules that get combined are "you fall with some acceleration" and "portals can change your direction").
Contrast this with Tutorial Level, where the designers sit you down and explicitly inform you about the game's mechanics rather than let you learn through experimentation.
- Antepiece: When a number of "challenges" involve related ideas, but initial ones don't present anything like the same challenge. They exist purely to expose some concepts that will be useful later.
- Broken Bridge: The designers might want to put you in a room that you can't get out of without working out the new thing they are trying to instruct you in. The question arises though: what if they try to go out the way they got in? They might not be able to immediately see how to get through this room, and instead think "oh I'd better go and check to see if I missed something in early parts of the game that will be useful here". So, when you have such a room, you want to make it so the player can't go back you want to lock the door, or break the bridge they used to get here.
- Camera Tricks: Devs want to make things very clear in these situations, so they'll often use camera techniques. They might, for example, avoid confusion about locations by trying to get it so that every relevant object will be on the screen at the same time.
- Equipment-Based Progression: devs may place initial limitations on the player's abilities and lay out the game such that you only need *this* thing for *that* part. This avoids a bit of confusion for a player thinking about what they should use in a given place.
- Foreshadowing: Sometimes a level designer will give you the opportunity to have a good look at the area of a level you're about to go before you go there, allowing you to asses the situation. This happens for the "energy ball room" in Half Life 2: Episode 1 and for many shooting arenas in FEAR.
- The Law of Conservation of Detail: there are things you'll do in a level that don't seem like such a big deal, certainly they're not very challenging. But they might be teaching you certain controls in a subtle way.
- Minimalism: Designers want the player to focus on learning something that could potentially be very important, so instructive level-bits will often contain a small number of elements. They don't want you to be distracted by the nice way the light shines through the trees over there, or whatever.
- New Weapon Target Range: Designers give the player a new tool, and set up the next area in such a way that it perfectly suits the tool's use.
- No Sidepaths, No Exploration, No Freedom: Constraining the player means that you can make sure that he gets introduced to the exact ideas you want to introduce to him or her.
- Teaching through Accident: When designers encourages players to do something that may not actually help them, but allows them to discover something new regardless.
- Videogame Difficulty Tropes: There might be dynamic difficulty adjustment used in this kind of level design, or just generally less aggressive enemies or something like that.
- Video Game Rewards: To hammer home "you have learned something specific", it is good to give the player some kind of short-term reward for their successful experimentation. Not a "you have won the game", or indeed a "you have done something HUGE AND DIFFICULT", but simply a "you have showed some cleverness" - a medium-sized reward.
- Training Dummy: something you can practice moves on without getting hurt.
- Super Mario Bros.'s 1-1 is considered one of the most well-crafted levels in gaming for successfully making use of almost all the above subtropes within the first few seconds of gameplay to teach all its mechanics. Series creators Shigeru Miyamoto and Takashi Tezuka break it down themselves here. It has also been analyzed on Anna Anthropy's blog, here.
- Metroid uses a few different teaching techniques.
- Many of the series entries begin with you having a choice about whether to go left or right. Most games are about going right, so there's a good chance that players expecting Metroid games to be normal games will go right. However, going right in the original game takes you to a dead end, communicating two things to the player: firstly, that this game is not a normal game, and secondly that this is a game about exploring, where you have multiple options about where to go.
- In the second room of Super Metroid, there's a small step you have to jump up on, in contrast to the many stairs in the rest of the area. This forces you to jump at least once and get a basic understanding of how the jump mechanics work, before you're pressed by time in the escape out of the area. You also meet Ridley there in a mock Boss Battle to test out your shooting skills.
- The original Prince of Persia subtly introduces several mechanics during the first few screens.
- In the very first room (the cell you're thrown into) there's nothing of interest apart from two dead-end platforms, above and below you. Dropping onto the lower platform makes one part of the floor shake; a curious player will investigate and run onto it, making it fall, thus telling that shaky floor parts are Temporary Platforms. Now, a first-time player will probably fall clumsily through the newly-made hole into a two-storey drop, further telling that falling too high will damage you.
- Now, to the left is a corridor with a closed gate at the opposite end, an easy pit to jump over, and a slightly raised floor tile between them. Jumping over the pit onto the tile reveals it as a switch that makes the gate slowly raise open. Slightly later there's a similar situation where the switch is easily placed directly before the gate, but there's a harder-to-see second switch between them that closes the gate. Walking onto it forces the player to go and press the first switch again, but now they should know that there's two kinds of gate switches.
- World of Warcraft has kinda gotten into this a bit in recent raids, even though you also get an ingame journal explaining the encounter mechanics. For example, before you fight Nazgrim in the Siege of Ogrimmar, you fight through groups of the same soldiers he calls in during the fight, so you'll already know what they do. Getting to Siegecrafter Blackfuse requires you to jump into pipes (and the enemies you fight are seen emerging from them) before the actual fight requires at least a few players using another set of pipes. Said enemies also use a number of abilities that appear in the fight proper as well.
- Mega Man X is famous for its intro level intuitively teaching players the controls and many elements of basic game strategy. The different enemy types will teach the player how to jump over enemies and their projectiles, demonstrates the different behaviors of enemies, and how to ride on certain enemies and vehicles, including that some enemies come in parts that can be destroyed separately. The level also features enemies that can destroy the ground and parts of the ground that fall apart, showing off the dynamic layout of stages and stage elements, and giving the player a safe chance to learn how to do X's Wall Jump when they fall into a pit that they have to climb to get out of, and reward their feat with a second pit immediately after with a health power-up. The stage ends with a Hopeless Boss Fight against Vile that Zero saves you from, the two demonstrating usage of the Charge Shot, dash command, and Ride Armor; the latter two mechanics show up in Chill Penguin's stage, the first stage most walkthroughs advise, and you can try out the Charge Shot there. In terms of story the stage sets up Vile as a general of Sigma that overpowers X and is then chased off by Zero, X's friend, which sets up a character arc for X to realize his potential and grow stronger.
- Shovel Knight teaches you all of its crucial mechanics through the first level's design. Piles of dirt are placed on the ground, encouraging you to figure out how to use the shovel right before you encounter your first enemy. Raised platforms require you to jump, and a breakable block that must be struck from above to proceed teaches you that you can strike down with the shovel. Right after this the downward strike must be used to bounce off a bubble to get to a higher platform and a gem located to the side of an area where the downward strike must be used teaches you that this move can be cancelled with the regular shovel hit. To beat the level you also have to pass through two breakable walls, one of which is marked and one of which isn't, teaching you about hidden rooms.
- Most Kirby games have a raised platform near the start of the first level that's too high to jump over and requires Kirby to fly to get over.
- The opening segment of NieR: Automata has small windows that appear periodically to tell you what button does what and that's it. Everything else you learn about the combat is taught without you even realizing it. In fact, the very first segment that's an arcade style Shoot 'em up teaches you EVERYTHING about the basics of the game's combat mechanics you need to know: That shooting with the R1 button lets you destroy pink bullets, that melee strikes let you destroy purple ones, that you can choose between close and long range fighting and you'll need to strategize accordingly. By the time you reach the first on-foot section, you already know the controls, because they're exactly the same as the flight sections. The only things new that you learn in the on-foot combat is how to read when an enemy is about to attack (their eyes flash red before they strike), and practice dodging melee attacks. Nier: Automata is also notable in how stiff a gatekeeper it is. To go from the first shooting section to the first boss takes about 30 minutes, and there are NO save points until you beat the boss. You die, you start from the beginning. The unspoken message is clear: you are NOT moving forward until you prove to the game you have all the skills you need down cold.
- This video here talks about how (the remixed) Flying Battery Zone in Sonic Mania teaches the player how the level's unique mechanics work in a much better way than the original's. In both versions, the foot-boosters are the first things encountered, which boost the player into an area that allows them to enter and run around the mesh pipes to know how they work. Unlike S3&K's Flying Battery Zone, the first hazardous mechanic is shown to the player in a relatively safe environment where the player's grabs onto a hang bar that takes them near but out of range of a flamethrower trap, instead of S3&K's where it is very easy to run straight into the first flamethrower trap due to it being initially offscreen until you run towards it.