"Xenosaga Episode I" is a role-playing video game; the player controls a party of characters, navigating them through a variety of environments tied to the progression of the story. Gameplay segments are separated by story sequences told mainly through traditional full-motion cutscenes. Exploring environments, the party can collect a variety of items, some of which can be used in gameplay to boost a character's statistics or restore health. During the course of the game, a database is unlocked that documents the game's story events and terminology. The player can access several mini-game "plug-in" systems through Shion's portable console, and an e-mail system that allows players to make playful decisions that have little significance to the main plot. The console can also be used to access to cleared areas of the game; these grant access to side quests separate from the main storyline.