In video games, particularly 2D platform games, there are sometimes some weird platforms and surfaces. The most common variation of them is when you can jump through them from below, yet they are solid when you're above them.

In 2D platform games, it can be assumed that your character is not jumping 'through' the platforms, but rather jumping 'in' or 'out' of the 2D plane (ie. the platforms may not be in the same plane; it just looks that way to the player).

In some cases, it's possible to drop down from that platform (most commonly by ducking and then hitting the jump key). In other cases, it's impossible to go back down from said platforms except by walking off the edge.
%% Please add examples in alphabetical order.

* Some ''VideoGame/{{Action 52}}'' games had platforms not solid from below.
* ''Videogame/{{Alien 3}}'' had these kinds of platforms.
* ''Batman - Return of the Joker'' has these platforms, too.
** As did the 8-bit ''Batman'' game available on home computers.
* You can pull yourself up of platforms like these in ''VideoGame/BionicCommando''.
* The Wii version of ''ABoyAndHisBlob'' has platforms that are not solid from below but solid from above. You can't drop down them unless you happen to have a hole with you.
* In the first ''VideoGame/BubbleBobble'' game, every platform tile is one. The possibilities of these platforms are commonly experimented with in the levels, too. Later Bubble Bobble games have these kinds of platforms as well.
* You don't hit your head against thin platforms from ''VideoGame/{{Braid}}''.
* ''Franchise/{{Castlevania}}'' games (particularly in ''VideoGame/CastlevaniaTheAdventureRebirth'') often have platforms that can be jumped through from below. There are also stairs which partially behave that way.
* Both ''VideoGame/ChipNDaleRescueRangers'' NES games have these platforms.
* ''VideoGame/CommanderKeen'' had the full works... not just the vertical version but one-way left or right blocks in the first trilogy, as well as platforms that you could fall through but are solid from below.
* ''VideoGame/{{Contra}}'' has lots of platforms which are solid from above. It's possible to go through them from above by ducking and hitting jump.
* Most of these kind of platforms in ''WesternAnimation/DarkwingDuck'' NES game can be jumped through, walked on and it's possible to hang on them.
* ''FancyPantsAdventures'' uses them after Fancy Pants Man jumps or runs upwards; the platforms don't allow him to drop down, though usually, he can just drop off the side.
* ''VideoGame/DonkeyKongCountry'' has these. ''VideoGame/DonkeyKongCountryReturns'' manages to recreate them in a 2.5D game -- even though the platforms and Donkey Kong are rendered as 3D models, Donkey Kong can still jump up "through" them and then land on them, and it's rendered as if he were passing "in front" of the platform instead of through it, yet he doesn't visibly move along the Z-axis.
* ''VideoGame/EarthwormJim'' had some platforms that can be jumped through from below.
* ''VideoGame/TheFairylandStory'' was based around these, like ''VideoGame/BubbleBobble'' but predating it.
* Both ''TheFlintstones'' NES games had those kind of platforms.
* Many ledges in ''VideoGame/GhostsNGoblins'' series behave like that.
* ''GrandChase'' uses this, letting you drop off from platforms by pressing down, but not in rooms that have a BottomlessPit.
** The earlier ''MapleStory'' had this as well. Jumping down was handled by holding the down key and pressing the jump key once for each descent.
* Toadstools in ''IndianaRodent''.
* Some platforms in ''VideoGame/JackieChansActionKungFu''.
* Numerous platforms in ''VideoGame/JazzJackrabbit'' work that way.
* ''VideoGame/JetSetWilly'' (and its predecessor, ''ManicMiner'') assigned each square on the screen one of four elemental types, colloquially referred to as "Air" (fall through from all directions), "Water" (can jump through from below and pass sideways through, but not travel down through; basically, this trope), "Earth" (impassable from all sides; can stand on, but not walk or jump through) and "Fire" ([[CollisionDamage kills you on contact]]). And yes, water was often an instant killer, making water blocks technically "Fire" type...
* Clouds in ''JumpBug'' are solid from above but not from below.
* ''VideoGame/{{Jumper}} Two'' and ''Three'' features solid-from-above platforms. ''Jumper Two Editor'' (version 4.x) changed these to "Ghost Platforms" to HandWave a certain bug in previous versions[[note]]Put a gravity-obeying object like a crate on such platform, then have Ogmo drop below and the object will drop off a platform ''by itself''.[[/note]] and added a variation for three other directions.
* ''VideoGame/TheJungleBook'' NES and SNES game had these platforms.
* ''VideoGame/KidIcarus'' NES game has this in several places.
* ''VideoGame/{{Kirby}}'' games feature platforms which are solid from above but you can jump through them from below. There are both can-be-dropped-down and cannot-be-dropped-down variations. Since you drop through them by just pressing Down, Kirby can't duck on thin platforms.
* ''LinusSpacehead'' and ''Linus Spacehead's Cosmic Crusade'' often use these platforms.
* ''LittleBigPlanet'' tries to simulate these. There are three 2D planes you can be on (foreground, middle, and background), and jumping up above a platform on an adjacent plane automatically shifts you into that plane so you can land on it. You can also drop down from a platform by moving towards the foreground, but not towards the background.
* An unusual example is from ''VideoGame/LodeRunner''. Some of the trap blocks are solid from sides but can be fallen through from above.
* A few moving platforms in ''VideoGame/TheLostVikings'' series behave that way.
* There isn't a single solid ceiling in ''VideoGame/MagicalWhipWizardsOfPhantasmalForest''. One of the game's levels is nothing but these platforms, stretched the whole width of the screen. One has to be careful not to accidentally jump up to a higher platform, as there is no way to go back down.
* Some ''SuperMarioBros'' games will also feature these kinds of platforms.
** [[InvisibleBlock Invisible coin blocks]] can only be revealed by hitting them from below -- from any other side, you'll go straight through. But once they're revealed they turn into ordinary used blocks that are solid from every side.
* ''VideoGame/MegaMan'' games don't have a lot of them. However, certain stage-specific objects, like conveyor-powered small platforms in Sheep Man's stage in ''VideoGame/MegaMan10'', are not solid from below.
* In ''VideoGame/{{Miner 2049er}}'', platforms are generally directionally solid; this is most obvious in the "Lillipads" levels.
* The ''VideoGame/MontyMole'' games have many platforms like this.
* ''VideoGame/MoonCrystal'' starts off with tree branches being like that and it continues with every thin or moving platform.
* ''{{N}}'' and its commercial remake ''N+'' have four varieties of directionally solid platforms. It's just one block, but it appears turned in every single direction, resulting in platforms you can fall through from above, but not jump through from below and vice versa and platforms you can go through from left to right, but not the other way around and vice versa.
* Present in ''VideoGame/{{Predator}}'' NES game.
* ''VideoGame/{{Psychonauts}}'': In some locations, it's possible to jump while directly under a trampoline. You go through the trampoline, but are bounced even higher.
* ''VideoGame/{{Purple}}'' features such platforms for ''every'' direction, including standard "solid from above" hills.
* The original ''VideoGame/{{Rayman}}'' does this too, in the most frustrating variety imaginable: One ''entire'' room in the game is made up of bouncy platforms that you can jump up through, and the goal is to get to the bottom. It's ''incredibly'' easy to take one misstep and bounce all the way to the top of the room.
* Platforms and ledges in ''{{Ristar}}''.
* If you go through one of those platforms in ''{{Shantae}}'', there's no going back down.
* ''{{Shinobi}}'' games had this thing going on.
* Many areas in ''SonicTheHedgehog'' games feature these platforms. For an example, Green Hill Zone is full of them.
* In ''Spacestation Pheta'', climbing a ladder with a floor above it will result in the player emerging above the floor, ''even if the square above contains a solid object''. If this is another floor, then it becomes a Directionally Solid Platform: the player can jump to rise above the second floor, but can't get back down.
* The ''VideoGame/SuperSmashBros'' series features a lot of these. With platforms that can be dropped through, you can hold the analog stick down to drop straight through them without even landing on them.
* You may ''build'' these in ''VideoGame/{{Terraria}}''. You and most monsters may drop through them voluntarily, but Slimes and Demon Eyes can't. They're also good for grappling.
* Platforms in on-foot sections of ''Ultimate Stuntman''.
* Often present in ''{{Vectorman}}''.
* They're in ''VideoGame/WizardsAndWarriors'' series, too.
* A few ''Franchise/WonderBoy'' games have platforms like that. So do ''VideoGame/AdventureIsland'' games.