8-bit CPUs instruction sets were really aimed towards assembly programming instead of being compile targets for "high-level languages" like C, and coding tricks are required (not optional) that are not possible in C, like self-modifying code or exact cycle-timing of instruction sequences (e.g. to fit into a video scanline). Some more obscure languages were not that bad (e.g. Forth), but most game programming on 8-bit machines was definitely done in carefully hand-crafted assembly.
This only changed slowly with 16-bit machines like the Amiga or Atari ST, they had more memory, the Motorola 68000 instruction set was more suited for compiled languages, and the custom chips (like copper and blitter) freed the CPU from many graphics tasks. Yet even on those machines the critical parts were usually written in assembly.
This only changed slowly with 16-bit machines like the Amiga or Atari ST, they had more memory, the Motorola 68000 instruction set was more suited for compiled languages, and the custom chips (like copper and blitter) freed the CPU from many graphics tasks. Yet even on those machines the critical parts were usually written in assembly.