Game Companion: Assassins Creed Odyssey is an unofficial app developed by Uyt Development for Android users. The app is designed to be a comprehensive guide for Assassin's Creed Odyssey gamers. It features a map that shows all the important locations in the game, including Elysium, Underworld, and Atlantis. The app also provides a detailed description of each location, which can be filtered by type.

The app allows users to mark locations as completed, which helps them keep track of their progress. It also has a light and dark theme, making it easy to use in any lighting condition. Users can search for locations by their name or description. The app is free to use and does not require any in-app purchases. However, it is important to note that this is an unofficial app and the developer is not affiliated with Ubisoft in any way.