In addition to Der Die Das, I’ve been working on German Plurals, a fun German plural noun quiz game in which the player tries to guess the correct plural form for a set of nouns.

Contains 350 nouns adhering to the Goethe-Institut A1 examination, separated into 7 groups of 50.
Words are pronounced uses speech synthesis.
Each correct answer earns one point. A false answer resets the score to zero.
Progress and difficult nouns can be viewed from a list overview.

Although the game is still in the early prototype stage, I posted discussions to Duolingo and Reddit with a link to an online playable version and asking for feedback. Interest was far lower than with Der Die Das, with only 85% less of a response rate. Thus at the moment it make no sense in continuing development of German Plurals, instead I will continue solely developing Der Die Das, and re-evaluate German Plurals once Der Die Das has been released for testing on iOS and Android.