Q*bert

Q*Bert is a true classic that seems to be somewhat forgotten. It's not too strange though, since it is 35 years old. It was an arcade game made by Gottlieb in 1982.
It was converted to a lot of platforms, got a lot of sequels including Q*Bert's Qubes (1983), Q*Bert 3 (1992), Q*Bert 2004, Q*Bert 2005, and Q*Bert Rebooted (2014).
Although it may not be widely well known any more, it certainly has been popular, as all ports, remakes and straight up rip-offs can attest to.
My first contact with the game was the clone Q-Bic (1992) for the Amiga 500.

Q*Bert Arcade

Although not as widely known as Pacman or Tetris, Q*Bert certainly is as iconic.
Maybe not that surprising, since the character was developed before the actual game.
His snout was originally supposed to shoot boogers at the enemies and the game was briefly titled "Snots and Boogers" during development.

Early concept sketch showing Q*Bert shooting

@!#?@! was another suggested title, mimicking the comic-book style swearing that Q*Bert rewarded the player with if he got caught by an enemy (together with a garbled voice synthesis).

The goal of the game is to switch all the squares into a target color by jumping on them while avoiding falling off the pyramid or getting caught by the enemies.
The game gets gradually more complex as later stages have you jumping on squares multiple times to reach the target color, or having the squares revert back if you jump on them multiple times.
Since the complexity of the later stages make it more and more like a puzzle game, this probably makes Q*Bert the very first Action Puzzle game.
It did not manage to be the first game with an isometric view though, since Zaxxon (1982) was released some moths earlier.

As you progress through the game more innovative enemies appear, such as the snake Coily that chases you around the stage or the, Slick and Sam that changes back the squares they jump on and Wrongway that is turned 90 degrees and jumps on the "wrong side" of the cubes.

When Q*Bert falls off he pyramid in the arcade there is actually a physical clunk generated by a pinball table part smashing against the inner wall. Quite innovative, but not that surprising considering Gottleib mainly manufactured pinball games.