This thesis reviews research about the basics of production and optimization steps in creating assets for the video game development and mastering the software used for it. This work aims to create a 3D adventure game with all the needed elements and making them optimized and prepared for platforms with different strengths and configurations. The software used to create video game assets are presented, and the Unity engine itself, in which all the game assets are assembled into a complete game. The practical part includes the process of making the assets and the final game with a description of the work in Unity engine. The work includes an explanation of the game optimization process for mobile platforms.