The Hedgehog Engine is a graphics engine, and has no bearings on gameplay style. It is not compatible with the PlayStation 2's, Wii's, and Nintendo 3DS's hardware because they are not powerful enough to handle its next-gen lighting and visual effects. The engine is not to be confused with Havok, which is related to certain physics tasks, or Sonic Team's in-house engine used for gameplay. Hedgehog Engine is also used in the game Sonic Generations. Sonic Generations was in development for two years from 2009.
The engine was in development for three years. As well as featuring camera position changes and a blend of classic elements from other Sonic games, the Hedgehog Engine also uses a revolutionary new piece of technology. This was called the "light-field", which can create CGI quality graphics in the in-game graphics system. The basic concept of the Light-field is that light bounces off every single thing on screen, creating an ultra realistic look on the area around. Also, not only did the graphics around Sonic change, but so did Sonic's model. Light is reflected off of him too, to make sure that he didn't look "out of place" as many reviewers would claim from past Sonic games.
A successor to the original Hedgehog Engine named "Hedgehog Engine 2" has been developed and was confirmed by Takashi Iizuka that Sonic Forces released for PC, PlayStation 4, Xbox One and Nintendo Switch runs on it, being the first game to do so. The main features of Hedgehog Engine 2 are the Global Illumination, Physically Based Rendering and improved shadows. The engine was developed by Sonic Team to improve lighting and shadows and other problems that occured with the original Hedgehog Engine.
While Phantasy Star Online 2 is the only game outside the Sonic the Hedgehog series to use the Hedgehog Engine, Sakura Wars (2019) and Tokyo 2020 Olympics: The Official Video Game are currently the only games outside the Sonic the Hedgehog series to use the Hedgehog Engine 2.
They are also the only games that are not developed by Sonic Team in use of the engine.
In the US TV commercial for Sonic Colors, the Hedgehog Engine icon was shown.