"Everything Is Smashable" Area

Sometimes game makers want to show how epic a battle is by having the arena you're fighting in slowly fall apart as enemies (or you) launch attacks or get tossed around. Sometimes they want to show off their awesome physics engine, and sometimes... sometimes they just think being able to blow everything up is really, really cool.

Enter the "Everything Is Smashable" Area, a location where environmental and structural objects can be shot, smashed or blown apart just as easily as the Mooks guarding them. Usually this is done for the purposes of collecting points or items, but occasionally destroying objects or walls en masse is necessary to progress or, in more cathartic instances, the whole point of the game.

Examples of "Everything Is Smashable" Areas include:

The Barrel Full of Barrels in Kingdom of Loathing.
There's a game-mode in Godzilla: Unleashed where you get points for...well...destroying a major city. Certain buildings are worth more points than others and famous landmarks (e.g., the Tokyo Tower) are worth the most points.
Left 4 Dead 2's Swamp Fever had a level where the survivors must make their way across a rickety, highly destructable bridge. The structure is slowly chipped away at by gunfire and zombie attacks, and god help you if you throw a molotv. Lots of fun on Versus on the zombie team.
Blast Corps was made of this, except for the trees.
Half Life has a few rooms filled with nothing but smashable crates.
- Half Life 2: Episode 1 features a duel between Gordon Freeman and a Combine gunship in a large, rickety wooden building which is slowly reduced to rubble by surface-to-air missiles and heavy machine-gun fire. The fight gets progressively more difficult as available cover is destroyed.
  - Or easier depending on your play style. After all, if a part of the roof covers you from the gunship's fire, it covers the gunship from your fire too. Opening up more of the roof can tip the advantage to the player, as your rocket launcher requires a few seconds of uninterrupted line of sight to hit as the gunship circles past you, while the gunship's cannon hits almost instantly.
The Baldur's Gate: Dark Alliance games were pretty heavy offenders.
The main way of getting studs in almost every Lego Adaptation Game.
- And the best way of handling puzzles. When in doubt, attack the scenery.
The storehouse just outside of Hyrule Castle Town in The Legend of Zelda Ocarina of Time, during the parts of the game when Link is a child. An NPC in the room hangs a lampshade on it by mentioning how Link can "let off some steam" by destroying the jars.
- The final boss arena is this for the final boss- you can maneuver him into smashing the various bits of rubble around, releasing item pickups for you. Handy.
One of the castle levels in Wario Land II consists of you smashing through a bunch of walls.
This sort of happens in Kingdom Hearts II. There's a minigame wherein you have a room full of boxes to smash, but you have to be strategic about it in order to get any sort of reward.
This was the entire point of classic arcade game Rampage.
Earthworm Jim 2 had the level "Lorenzen's Soil", where Jim's gun needed to be used to shoot a path through dirt.
Red Faction and Red Faction 2 live on this trope, such that it shocks you when you finally come across a surface that you can't blast your way through. Red Faction: Guerrilla ups the ante even further by setting the game on an Everything Is Smashable Planet.
More or less the entire point of Space Invaders Get Even: Every destroyed building and enemy increases your timer by varying amounts, which also doubles as your lifebar. As might be expected, abducting cows and visiting Stonehenges (yes, it's a plural, for whatever reason there's one in pretty much single level) increase it the most.
Most of The Force Unleashed is like this, until Disappointing Last Level sets in for the final level. The Kashyyyk prologue is especially notable, though, crammed full of trees you can cut down with your lightsaber and throw around with the force, and grass that ripples as you blow things over it. Also Wookiee-tossing.
Many games that advertise themselves as featuring destructible scenery will have a few of these and make sure they're prominently featured in the trailer. The rest of the game? Not so much.
The Japanese game Hakaioh - King of Crusher is based on this trope. Your character usually has violent rampages in which he smashes everything in the room, brought on by some kind of a weird talking flying demonic beetle with bat wings. Taken Up to Eleven in later levels when the main character is turned into a werewolf of some kind, a dinosaur, a Godzilla expy and finally a dragon, just so you can destroy bigger stuff.
Non-video-game-example: the mall in Zombieland.
- Psh, The Blues Brothers did it 20 years ago. With cars.
The "Mayhem Missions" in City of Villains.
Every level in the Ghostbusters video game. But especially the hotel level, which is a Continuity Nod to the movie, where they destroyed goddamn EVERYTHING in a hotel.
The bamboo forest in the second part of the fight against General Tsao in Sly 3: Honor Among Thieves.
The Overlord series of games allows you and your ravenous horde of gremlins to smash just about any and every inanimate object aside from trees, bushes and rocks. In fact, doing so is often necessary to find treasure. Plus commanding a ravenous horde of gremlins to tear apart a tranquil village including burning down the houses is immensely entertaining.
No More Heroes Desperate Struggle has the room where you fight Matt Helms. In it, almost literally the only things you can't break are the floors and the walls.
Later on in the game, in Serious Sam III BFE, you go through some Egyptian ruins where all the pillars, archways and most of the walls are destructable. Very fun with crates full of infinite rocket launcher ammo and C4.