The porn video tag "sex-game-playthrough" refers to a video that showcases a playthrough or walkthrough of a sex game. In this context, the term 'sex game' typically refers to adult-themed interactive games where players participate in various sexual activities with virtual characters or partners. The tag indicates that the video documents the player's progress and experience within the game, demonstrating how to navigate through different levels, scenes, or choices in order to achieve specific goals or outcomes related to sexual scenarios or fantasies. These types of videos are usually meant for adult audiences who enjoy engaging with sex games and want to see various ways to explore and unlock content within the game.