As it now says in the Google Play App description of Pulsar Chess Engine explains it best, below.
Pulsar Chess Engine is also on iOS & Mac and accessible and there are Linux, Windows, and Mac binaries at http://www.lanternchess.com/pulsar/
The apps have no real mods to search itself and use pulsar2009b, except bugs in FR castling were fixed in the apps.
I started pulsar in 98 as a Winboard engine and taught it variants between 2002-2009.
The levels are unique to the apps and take advantage of changing search parameters but also now evaluate for our new easy level.
From the Google Play Description:
The board in Pulsar Chess is Accessible by Talkback, for the blind and visually impaired. Only direct tapping is supported, not swiping. Tap on a square, and it will speak what's on the square such as "e2 - white pawn". Double tap to select the square with Talkback on. There is also speak move. This speak move and tap on square info is in English as well as Spanish, Italian, French and German. Talkback can normally read text on buttons and labels etc, but a board is a collection of images. To be accessible, the board has to be programmed to return text when the tap is in the space of a square.