Game design, a subset of game development, is the process of designing the content and rules of a game in the pre-production stage and design of gameplay, environment, storyline, and characters during production stage. wikipedia.org

Game development is the generally involved and lengthy process of creating a video game. Development is undertaken by a game developer, which may range from a single person to a large business. wikipedia.org

C# (pronounced see sharp) is a multi-paradigm programming language encompassing strong typing, imperative, declarative, functional, generic, object-oriented (class-based), and component-oriented programming disciplines. wikipedia.org

Android is an operating system based on the Linux kernel with a user interface based on direct manipulation, designed primarily for touchscreen mobile devices such as smartphones and tablet computers. wikipedia.org

A level, map, area, or world in a video game is the total space available to the player during the course of completing a discrete objective. The term "level" can also refer to difficulty level, as in a degree of difficulty. wikipedia.org

Unity is an integrated authoring tool for creating 3D video games or other interactive content such as architectural visualizations or real-time 3D animations. wikipedia.org