Tuomas Erikoinen discusses designing character-driven games that engage and retain players. He argues that focusing on a small number of exaggerated lead characters and discreet side-kicks can help build interest in characters over multiple games and franchises. This approach provides developers with a consistent vision and allows games and characters to expand into product families. Guidelines are offered for the number of characters, art style, and development process based on the target audience. The goal is to use strong characters and story to increase player engagement beyond individual games.