HPL Engine

The HPL Engine is a 3D game engine created by Frictional Games. The engine, named after the initials of horror author H. P. Lovecraft, was started in December 2004, as a thesis job for a 2D platform game "Energetic", released in 2005. The functionality for 3D games was added later, which culminated in Penumbra Tech Demo in 2006. In 2010, the first version of the engine (HPL1) together with Penumbra: Overture was released as open source under the GPL license, after the Humble Indie Bundle promotion finished.