Unity Engine is a multiplatform game engine built to "democratize" game development and is available as a free version and a Pro version with advanced features (and a stylish dark interface). Building games with Unity is done visually using the Unity Editor where you can manage assets and modify game objects without having to write any code. The game can then be exported to a variety of platforms with the Pro edition (and Pro Add-Ons) offering more options for export.
- 3D/2D Graphics
- Multiplayer Networking
- Mecanim Animation Engine
- Realtime Shadows and light mapping
Recently the Unity 5 edition was announced which will provide a 64-bit editor, physically-based shaders, real-time global illumination, support for nVidia PhysX 3.3 and the means to export to WebGL (meaning support for web games without the Unity Player plug-in).
The Unity Editor is composed of an asset manager, a what-you-see-is-what-you-get (WYSIWYG) editor window, a properties inspector and a debug console. Games are created by dragging assets (3D meshes or sprites) from the asset manager into the game world as game objects which contain a set of components which define how they are treated by the engine. For example, a game object would contain a Mesh Renderer component which combines a 3D mesh and a material to create the model in the game world. The game objects could also have physics-based components such as a Box Collider and Rigidbody component which determine whether they will be affected by gravity or if they trigger an action when another object passes through them.
Most components come with a set of properties which are used to tweak how they behave or can be disabled completely at the developers discretion. For example, the Rigidbody component has a property for disabling gravity on the object while still allowing it to physically interact with the other objects in the world.
Integrated into the editor is the Unity Asset Store, which features free and paid-for assets which can be downloaded directly into the current project. These assets can be a set of materials, complete 3D models with associated animations or script packages that provide you with pre-built gameplay controls or editor
- NGUI: Assets for creating complicated GUIs. The author of this tool was later hired by Unity to work on their internal GUI system.
- Playmaker: Editor extensions for building AI or gameplay using visual scripting without having to learn code.
- prime: A publisher of several plug-ins for interacting with the hardware or external systems of mobile devices.
The Pro version of Unity includes a lot of advanced features and optimizations and is targeted towards developers looking for professional quality. It costs $1,500 (or $75/month) and features audio filters, HDR lighting, full-screen post processing and the means to set a custom splash screen.
Along with the Pro edition are a set of add-ons which are geared specifically towards certain platforms and provides optimizations and specific features for that platforms. The add-ons require a Unity Pro license and can be purchased as a one-off upgrade or with a monthly subscription. As of Unity 4, the Pro edition includes the Windows Phone 8 Pro, Windows Store Apps Pro and BlackBerry 10 Pro add-ons.