As seen in the very beginning of the first book in the Heavy Metal Thunder series:
Heavy Metal Thunder is not a novel. It is a game, the first in a series in which you play the role of the protagonist. You begin reading at section 1 and then, depending on the choices you make, turn to the numbered section you are directed to read. The game ends when you reach the end of the journey… or when you die.
The rules of the game are given as the story unfolds, plus there is a handy index in the back. Eventually you will have to keep track of your inventory, stats, skills, experience points, and so on. The journey will be brutal. Because the universe is cold and uncaring, you will need to be cunning and ruthless in order to survive. As you progress through the game, your character will grow in strength and experience. In future installments of the Heavy Metal Thunder series you will rise up through the ranks of the Black Lance Legion, so be sure to keep your character data so that you can transfer it to Heavy Metal Thunder Book Two: Sol Invictus.
Variant rules for non-nerds: If you loved Choose Your Own Adventure books back in the day, but the idea of keeping track of skills and equipment sounds altogether too complicated and nerdy, then feel free to simply follow the branches of the story and make choices as you see fit. No one will fault you for enjoying the story in a non-nerd fashion.
For more info about the series, check this out: https://heavymetalthunderseries.wordpress.com/rules-of-the-game/