Atarashi Racket started way before Pixel Tennis was born.
4 students of the TGM Vienna are going to build their own game that is based on Fantasy Tennis gameplay. This project seems very mature. They point out which tools they use to create the game and they keep posing updates either on their homepage or on their facebook group. There are some screenshots that are showing a court, a player model and their animated logo - sadly nothing related to gameplay
A public beta was announced for March 2017, but they were not able to keep up the date due to personal reasons.
To my mind, this is the project with the highest potential, so keep up guys!
http://atarashi-racket.com/
https://www.facebook.com/groups/922976937741199
The facebook page is updated more frequently than the homepage. As of 11/2017, they are searching for more team members as 2 people left. Link (facebook registration required)