Blu-Play Overview

Blu-Play is basically a fancy name for Blu-Ray Java, also known as Blu-ray Disc Java or BD-J. Developer mr_lou coined the term "Blu-Play" to give the software a more distinguishing name, one that would stand out and make it seem more appealing than simply "Blu-Play Java".

For more information regarding Blu-Play, see Blu-Play.com.

What Is Blu-Ray Java

Blu-ray Disc Java, or BD-J, is a specification supporting Java ME (specifically the Personal Basis Profile of the Connected Device Configuration or CDC) allows for advanced content on Blu-ray Disc and the Packaged Media profile of Globally Executable MHP (GEM).

BD-J allows bonus content on Blu-ray Disc titles to be far more sophisticated than bonus content provided by standard DVD, including network access, picture-in-picture and access to expanded local storage. Collectively, these features (other than internet access) are referred to as "Bonus View", and the addition of internet access is called "BD Live." BD-J was developed by the Blu-ray Disc Association. All Blu-ray Disc players supporting video content are required by the specification to support BD-J. Starting on October 31, 2007, all new players are required to have hardware support for the "Bonus View" features, but the players may require future firmware updates to enable the features. "BD Live" support is always optional for a BD player.

Sony's PlayStation 3 has been the de facto leader in compliance and support of BD-J. The PlayStation 3 added Blu-ray Profile 1.1 support with a firmware upgrade and was used to showcase BD-Live at CES 2008 in January.

The above Blu-Ray Java explanation is taken from the Wikipedia article about BD-J.
Since that article was originally created, BD-J has advanced to many more devices, it can be played on basically any Blu-Ray player, it can be played on PS3, PS4 and Xbox One, the XB1 has the advantage of letting us play BD-J games from DVD.

Why Use BD-J/Blu-Play

BD-J lets us create games and software for several devices without the need of the device being modified, the games or software do not need to be designed specifically for each device as the same game will run on all devices, the main aim however for Blu-Play is to let us play homebrew on our games consoles and this can be done without the console being hacked.