The Guardian Legend

The Guardian Legend (known as Guardic Gaiden in Japan) was a hybrid Action Game and Shoot Em Up created by Compile for the Nintendo Entertainment System. Released around 1988, it's likely forgotten by all but the most hardcore of gamers, but this game did a great job of blending the two genres.

The game is about a female robot, codenamed "the Guardian", who is commissioned with stopping an alien-infested planet called Naju from crashing into Earth and killing everyone. To do this, she must set off ten strategically-placed explosives within the corridors (by transforming into a spaceship and flying through them) and defeat the bosses within.

Provides examples of:

Action Girl: The game's protagonist.
Apocalyptic Log: The corridors are peppered with notes from a deceased native of the place that tells you how to unlock some of the trickier doors.
Artificial Human: The Guardian herself.
Beam Spam: Many of the corridor areas have enemies that shoot a hail of lasers (especially at the end, when the laser-shooting ships have DEADLY beams). Also Eyegore, a multi-eyed skull boss loves this trope too.
Blind Idiot Translation: For example, in the manual, "The Guardian is a sophisticated aerobot transformer".
Boss Room: When you walk into a room and hear a warning klaxon and see indestructible pyramids closing around you, be prepared to fight!
- Or not. The pyramids close slowly enough that you can run out before the boss appears if you're quick!
Boss Rush: "Corridor 21", and "TGL mode", which puts you through only the flying stages.
Breast Plate: Perhaps justified, as the Guardian's main defense is a personal nigh-invisible force field.
Cool Ship: A strange variation, as the main character is the cool ship (at least, she can transform into it).
Cores and Turrets Boss: The very first boss of the game, as well as two of the organic corridor bosses.
Covers Always Lie: The North American boxart for the game looks like this, and has pretty much nothing to do with the game.
Dead Man Writing: When you first enter the labyrinth.
Degraded Mini Boss: One of the minibosses in the labyrinth stages appears as a regular enemy later, while still retaining its high health and brutal collision damage...
Difficult but Awesome: According to the UWW of this game, Lord Kat apparently discovered the ripple weapon being incredibly useful against the later bosses once fully upgraded. It's all a matter of using it correctly.
Earthshattering Kaboom: The goal of the game is to prevent this from happening.
- ... by making it happen to someone else.
Everyone Calls Him "Barkeep": The Guardian's name is never revealed in the game or the English instruction manual. According to the original Japanese manual, she is called "Miria" (full name: "Strongest Warrior System D.P., pet name Miria"). Fanon refers to the Guardian as "Alyssa".
Every Ten Thousand Points: The game rewards high scores by increasing you health meter every 30000 points. At the same time, the game will crash if you reach the score's Cap.
Everything's Squishier with Cephalopods: Zibzub, a red squid boss.
Evolving Attack: Both your main gun and your special weapons.
Exactly What It Says on the Tin: The Enemy Eraser.
Explosive Breeder: One of the enemies in the labyrinth areas is a blue spider that if left unkilled, turns orange, then red, then it splits into seven identical copies of itself. These individual copies can split even more, making things a little... complicated.
Extra Eyes: Grim grin. Eyegore too, but he ain't nearly half as tough as Grimgrin...
Eye Beams: Optomon likes this one a lot.
Fighter Launching Sequence
Flip Screen Scrolling: The labyrinth areas.
Game Mod: The "Secret Edition" rom hack, which takes the original's Nintendo Hard difficulty Up to Eleven by, among other things, giving Teramute a major upgrade, making him a new That One Boss.
Giant Enemy Crab: Crawdaddy, the boss of Corridor 2 (actually more of a lobster). One of the minibosses in the labyrinth areas IS a large crab that sprays bubbles about, though.
Giant Space Flea From Nowhere: It (a.k.a The Final Guardian), the Final Boss, who appears out of nowhere after the Boss Rush, just when you think you're home free. (In a bout of Fridge Logic, it shouldn't matter that much if you beat it or not, since it only appears after you've succeeded in your mission to blow up the planet.)
If You Can Read This...: All of the messages left to you by the last (good alien) survivor of NAJU comes in the form of giant monitors on the floor.
Insurmountable Waist High Fence - Those indestructible pyramids blocking your passage, until you gain enough speed upgrades to outrun the miniboss room ones.
Invincible Minor Minion: Mostly averted. While a few of the enemies seem nigh-impossible to defeat, they usually just have a ton of Hit Points. Of course, the Enemy Eraser decimates them with ease.
Hitbox Dissonance: The game is extremely lenient when it comes to what parts of your sprite take damage, and what parts of enemy sprites give damage (especially the bosses). The fact that the game is still Nintendo Hard in spite of this says something.
Kill It with Fire: The Fireball weapon. Especially at max level, when it can cause massive damage AND destroy enemy attacks.
Laser Blade: The Saber Laser and Cutter Laser weapons.
- They are also usually the easiest way to take down many of the otherwise challenging bosses. Lightsabers are just better, it seems.
Last Chance Hit Point: You will not die when your shields drop to zero. The next hit will destroy you, though.
The Lost Woods: The forest labyrinth area as well as the forest corridors.
Macross Missile Massacre: The Bombardier boss can fire no less than 12 or so missiles at you in one go. Its missiles, however, are very weak, especially when you fight it the second time round.
Mechanical Lifeforms: Most of the enemies infesting Naju.
Mercy Invincibility: Minimal, providing less than a second of protection, and only against small enemy collisions. Large lasers or enemy attacks do so much damage - sustained contact drains your shield almost instantly.
Mook Maker: LOTS of them...
More Dakka: The Guardian's default gun relies on this principle. The more chips she's carrying, the more bullets-per-second she can shoot. The enemies also get this trope - in some of the later corridors, you'll find yourself facing an inspiringly absurd number of bullets and missiles and flying enemies and EVERYTHING ELSE.
Organic Technology: Those enemies that aren't Mechanical Lifeforms.
Our Dragons Are Different: Teramute, a dragon boss that sprays fireballs. It's very easy, unfortunately.
Palette Swap: It's a NES game, so of course.
Rare Candy: The miniature Blue and Red Landers increase your maximum health and chip capacity, respectively.
Recurring Traveler: The Big Blue Lander shopkeeper.
Shoot Out the Lock: You have to do this for Corridor 1 by shooting out the gate, Corridor 5 by shooting out the corridor display panel, and Corridor 6 by using a special weapon on the gate.
Smart Bomb: The Enemy Eraser, which destroys all small enemies and projectiles on the screen. They become vital for surviving later parts of the game.
Sole Survivor: Aside from the Red and Blue Landers, NAJU was overrun by hostile aliens, and said survivor died sometime before your character arrives.
Spaceship Girl: Your main character is a female android who can transform into a spaceship.
Teleport Spam: Bombardier and Teramute love to do this, as do some of the mini-bosses.
Turns Red: Clawbot, Grimgrin (who also Shows Damage), and the Final Boss (who literally turns red).
Underground Monkey: LOTS of enemies, including some bosses.
Under the Sea: The Water area (although interestingly, some of the Water bosses are recycled for other areas).
Womb Level: The Organic area corridors.