Suspiciously Cracked Wall

...so, so many potential puns. Oh, and a gateway to the Dark World.

"Yes, waste your youth looking for secret passages in rocky tunnels."

—Comic Book Guy, The Simpsons Game.

In Video Games (and probably elsewhere) if you see a wall with cracks on it, you can be certain of two things:

There is something behind that wall.
It can be brought down with a well-placed explosive or hit.

See also Notice This for unsubtle hints towards locations done for the player's convenience rather than to actually hide stuff. Sister trope of Conspicuously Light Patch which typically means the same thing for the player.

Examples of Suspiciously Cracked Wall include:

The Legend of Zelda has many examples of these. 2D games also have fake wall cracks.
- Although this only helps with fake walls that aren't cracked, tapping them with Link's sword produces a different sound than tapping a solid wall.
- It helps with the cracked ones, too. The aforementioned fake wall cracks might even appear more often than real ones, and tapping with your sword saves you a bomb.
Zombies Ate My Neighbors, some levels are almost completely made of these.
Duke Nukem 3D has cracked walls you have to break with explosives.
The Simpsons Game has cracked walls which break when Homer hits them.
Cracked walls were a critical part of Star Fox Adventures.
Okami has walls with conspicuous (which is to say glowing) cracks in them; once Amaterasu gains the proper ability, these can be blown open with explosives.
- Battle arenas have cracks in them that can be attacked in order to escape from battle. The standard Zelda-style cracks are present, too.
These are used for Sequence Breaking in the first three Avernum games. Whether you can break the walls, and hence what you can avoid, depends on the level of the priest spell "Move Mountains."
The Metroid Prime games used this a lot, especially the first.
In Eversion, the more you evert, the more platforms become cracked and can be broken when Zee Tee steps on them.
In some Donkey Kong Country games you can destroy cracked walls with barrels or your rhino buddy.
In Batman: Arkham Asylum, removable walls—as well as being explicitly marked in Detective Vision—are visibly cracked and holed to normal vision.
The "classic" Spyro the Dragon games have these.
In Final Fantasy IX, in the chocobo minigame there are cracks in the mountains that can be dug for treasure. You can't see the chocobo break them because of the graphical limitiations.
In Max Payne there is a cracked wall that will resist your attempts to break it. Until you try to open the door, upon which the whole wall collapses, leaving only the doorframe standing.
In Banjo-Tooie, cracked wall = grenade eggs. Cracked floors also signal that they are able to be broken by a drill peck.
Defied in the fan remake of Quest for Glory II. Some of the walls of the streets of Shapier look damaged, but when you click on them the game tells you that while in other games a damaged wall can mean there's something behind it, that isn't the case here.
Abuse. If there is a crack, you can break it.
Wild ARMS 3 has noticeably cracked walls and Clive has bombs.
In the first two Quake games, several secrets could be discovered this way. Especially in the second game.
When playing Left 4 Dead as zombies, a glowing crack appears on walls that can be broken.
In the first God of War.
Killer7 has cracked walls that can only be destroyed by MASK de Smith's grenade launchers.
Cruelly, some cracked walls in La-Mulana must be attacked, but others blast you with lightning when you attack them. If there's a way to tell which is which, it's not immediately apparent.
In Day Of Defeat the walls that can be demolished by players' explosives are marked this way.
There's a notable moment in Devil May Cry 3 where you enter a room that doesn't seem to have anything in it... but there's a glowing crack in front of you. Turns out that there's a wall almost immediately in front of the door that you destroy to carry on.
If there's a cracked wall in Dubloon, you can crack it open with your supply of bombs. There's also a more common invisible variation.
Goes hand in hand with the Castlevania series. In fact, when the trope doesn't pop up in an installment, fans cry foul.
Metal Gear Solid tries to justify the trope by saying the boss deliberately blocked off walls, and that they are weaker than the ordinary walls.
In Pokémon Ruby, Sapphire, and Emerald there are certain areas in the overworld which can be turned into the entrance to a Secret Base. One of these is a strange hole in cave walls, which isn't so much a crack as a neatly-defined square hole. In a cave wall.
Unreal has a few and often requires to break them in order to advance. The Na Pali Haven level has even two of those.
Heretic's secret doors were always given away by a telltale light beneath them, or a subtle change in texture.
Deus Ex Human Revolution has a number of weak walls that your eyes' augments highlight automatically. Once the proper augment is purchased, you can punch through these walls, opening new paths or letting you get in a lethal surprise attack on enemies unfortunate enough to be close to that particular area. You can also knock them down with guns or explosives, but without the aug you'll have to pay very close attention or consult a guide.
The various games in the Paper Mario series each have their own cracked walls and a bomb-based ally with which to blow them up.
In Legend of Kay, cracked floors can be broken with the hammer, once Kay gets it.
Abuse also has these at times, which can be broken with any weapon.