Artifact Title: The Arkanoid only shows up in the backstory of the first game; it's not present in any of the sequels. Arkanoid DS takes it a step further and takes place in a completely different universe that doesn't involve the Arkanoid (or the Vaus, or Doh) at all.
Attract Mode: The NES version has a bug where you can continue from this and skip ahead several levels.
Bag of Spilling: Between levels, no less. Yeah, it would be great to start a level with Catch or Extend active... too bad you can't.
Bragging Rights Reward: Every unlockable in the DS version is purely cosmetic, including those requiring 100% completion to access.
Drought Level of Doom: Round 11 in Arkanoid, as well as similar levels that only have metal bricks that never release powerups. The ball will also speed up during these levels, which try to deplete your set of lives.
Elite Mook: The black spheres in Revenge of DoH, which only can be destroyed by touching the Vaus. In a way, the silver bricks as well, as they require multiple hits to finally break (unless the superball powerup is active).
Excuse Plot: You're a spaceship trying to escape from DIMENSION-CONTROLLING FORT DOH, by destroying blocks with a bouncing ball. Right.
"THE ERA AND TIME OF THIS STORY IS UNKNOWN. AFTER THE MOTHERSHIP "ARKANOID" WAS DESTROYED, A SPACECRAFT "VAUS" SCRAMBLED AWAY FROM IT. BUT ONLY TO BE TRAPPED IN SPACE WARPED BY SOMEONE........"
Fun with Acronyms: The iPod Touch version finally gives DOH a meaning. It's an acronym for the Arkanoid's crew's term for the thing on account of its control of the fabric of time-space, "Dominator of Hours".
The Goomba: In the games that have enemies, everything except the teleporting slimes that randomly move your ball to somewhere else in the level. They go down in one hit, and touching the Vaus kills them not you: Their purpose is not to inflict direct harm, only to throw your ball off trajectory. On the other hand, bosses do kill you with their attacks.
Invincibility Powerup: The superball/megaball power-up. For one, it could plow through the black sphere enemies. More importantly, it instantly plows through any brick - even gold and silver bricks. The only things it would bounce off of are the walls and the Vaus.
Leitmotif: While the stages themselves have no music playing, the "level start" music is iconic within the series - each game has its own remix of the original tune to start each level.
Luck-Based Mission: Playing the mid-Nineties Macintosh version on a black and white monitor? The odds were against you finding the right spot to beat Doh. True to an extent in all versions, because unless your grasp of geometry is at PhD level, you won't be able to precisely predict the trajectory of or aim the ball correctly every time.
Mutually Exclusive Powerups: Only one powerup is allowed at a given time. However, if you pickup a Disruption followed by a Mega Ball, the extra balls remain on the screen and can quickly clear the board. There is also a rare glowing powerup that combines these two powerups for you.
Nintendo Hard: Missions involving mostly gold bricks tend to be this. An entire mass of them with only a few, or even a single, destructable brick is a common sight in later levels.
Power-Up Letdown: The Twin powerup, as of Arkanoid II: The Revenge of DoH. The Vaus would split into two smaller copies that would move together. It only barely increased the surface area of the Vaus, was distinctly smaller than both the Extend powerup or the Image/Illusion powerup (the latter was longest, but only active while in motion), and there was a gap between the two Vaus units that the ball could fall through, costing a life. In either game, the Laser powerup if there were gold bricks between the player and breakable bricks on the playfield. Also, arguably the Player powerup. Yes, the extra life is always valuable. That said, it would remove any other active powerup on the Vaus - the player would have to decide if losing Laser, Catch, or Extend was truly worth the extra life.
Sequel Difficulty Drop: The original Arkanoid would only allow one power-up capsule on the stage at the same time, would not spawn any power-up capsules from silver bricks, completely lacked any way to destroy gold bricks, had a much less effective Dispersion capsule (the original would only split the ball into three; later games upped it to eight), and the game itself was completely linear (later titles would allow you to choose between at least two levels to advance to).
Sound of No Damage: The ball makes a different sound when it bounces off of a gold brick or a silver brick that needs more hits to break.
Updated Re-release: Arkanoid R 2000 is this to Returns, which adds 150 additional levels and even features proper bosses.