Here is a list of all files with brief descriptions:

firmware
SNAKE_STM32F3
Core
Src
main.c	: Main program body
libs
2dspace
2dspace.h	Definition of 2D space orientation types
game
game.c	Implementation of high-level game state machine module
game.h	High-level game state machine module controlling application flow
game_renderer
game_renderer.c	Implementation of snake rendering module for ws2812b matrix display
game_renderer.h	Snake rendering module dedicated for ws2812b matrix display
joystick
joystick.c	Implementation of joystick handling module (STM32 HAL)
joystick.h	Joystick handling module based on ADC (STM32 HAL)
snake
snake.c	Implementation of game logic module with low level state machine
snake.h	Snake game logic module with low level state machine
ws2812b
ws2812b.c	Implementation of ws2812b diodes handling module (STM32 HAL)
ws2812b.h	Ws2812b diodes handling module based on SPI (STM32 HAL)
ws2812b_matrix.c	Implementation of ws2812b diode matrix handling module
ws2812b_matrix.h	Ws2812b diode matrix handling module based on ws2812b driver
ws2812b_matrix_symbols.c	Implementation of ws2812b diode matrix symbols display module
ws2812b_matrix_symbols.h	Ws2812b diode matrix symbols display module