According to posters on Trueachievements, the game and several DLC have been delisted from the store, and can't even be re-downloaded by people that already owned them.

These include
Ninja Gaiden Sigma 2
South Park
Plants vs. Zombies
Street Fighter 2
Marvel Women of Power
Star Wars Rouge One
Aliens vs Pinball
Balls of Glory

Don't suppose anyone from Zen could comment on this?