Unity is a popular game engine because of its accessibility, simplicity, and vast amount of features. It has a big developer community and a free indie version available. Many successful games that have massive marketing budgets and are developed for major platforms, from PCs and consoles to mobiles (also known as AAA games in games industry lingo), have been made using Unity. More importantly, it is very popular in the indie community. Many highly popular indie 2D games were made using Unity. A major feature of Unity is being able to create your game once and then deploy it on every major platform.

Unity originated as a 3D engine, and as such has mostly been used to create 3D games in the market. However, as there is such a high demand for 2D creation tools with many 2D games being released, particularly with the popularity of app development, the developers of Unity have just recently released tools specific to 2D creation in Version 4.3.