Hello! Firstly a big thank you, the fact that you are reading this means you actually care about doing the right thing, and want to acknowledge the software you have used from other developers.
The olc::PixelGameEngine is open source and is released under the OLC-3 licence. This means you can use it freely, even for commercial projects. However, the licence requires that appropriate attribution is required.
After quite a few late nights, it’s finally here! PGE 2.0 is a significant upgrade on its predecessor, and is 100% backward compatible. This major revision brings in hardware accelerated sprites in the form of the olc::Decal, multiple rendering layers, and has been completely re-organised to make it easy to port to other platforms.
The features added were in response to the fantastic feedback from this community. You guys wanted to use it as a genuine game engine? Now you can.