Arkanoid

The C64 port of the game is notable for the groundbreaking score by Martin Galway, who was the first one to discover and exploit a glitch into the sound chip of the machine that, once exploited, was capable of triggering a sound sample playback, despite the chip not being designed to be capable of sound sampling at all.
The "glitch" creates a "virtual" 4th channel of sound that adds to the regular 3 sound channels of the SID Chip, thus effectively extending the scope of the sound chip past its design and intended limits.

Not satisfied and feeling it was not enough as a quantum leap forward in digital music pioneering, Galway also devised and programmed himself some weird procedural machine-language opcodes so that sound samples would be created not by using raw data stored into the ROM (as later composers would do, for instance Jeroen Tel and Rob Hubbard) but rather the sample would be generated mathematically-logicly by the game code itself, creating different types of low-resolution percussions and synthetic drum sounds that would act as the "virtual" 4th channel triggered by the glitch in the SID chip.
Actually, many decades later Martin Galway wrote that he had to adopt this avant-gardist solution to achieve this feat because there was not enough free space in the game's ROM for including sound samples, and thus the assembly codes, which occupied only a few bytes.

Add also the flanging effects of the other channels, the ominous bass square waves and the epic catchy tunes and here you have one of the most iconic and revolutionary soundtracks of the Commodore64 era, squeezing the machine to its limits with very minimal means by using humble machine language code.
Now, this was brilliant programming for an era where machine equipment was still fairly expensive by todays' standards, far from the contemporary code and big data bundles massed-in even for achieving very small tasks.
Vintage digital coding in videogaming (and science) and in early digital music was the contrary of all that is "tech" nowadays: the maximum achieved with the minimum, rather than the minimum achieved with the maximum.

As for the game, well, it is quite renown that, unfortunately, the most brilliant of Westerner programmers and composers (especially in Europe and the UK) most of their time had to work either for puzzle games, spoofs of famous franchise games, or outright shambled disaster games (with awesome underrappreciated personnel that would have made Japanese games look like amateurish if given the right means to do so). Good job nonetheless.