Sonic Lost Adventure is a 3D Sonic fan game modeled after the modern Sonic games--Sonic Unleashed (Day stages), Sonic Colors and Sonic Generations.
The game is modeled after the gameplay and level design of the modern Sonic games--Sonic Unleashed (Day stages), Sonic Colors, Sonic Generations--and seeks to bring you a similar experience. Sonic Lost Adventure will only feature the one level, Havok Harbor.
The current build is the same build that was shown at the SAGExpo 2014.
Before you start asking, no this game was not inspired by levels like Metal Harbor from Sonic Adventure 2. In fact, nothing in this game is related in any way to any other sonic title out there in terms of inspiration or concept.
You will need a decent computer to run this game properly.
There is also an Easter egg hidden in the game that hints towards the authors next project. Can you find it?