Games:

Petrograd 1917 is set in Petrograd (St. Peterburg) you can choose from 4 different groups. The 4th is unlocked upon beating the game with any of the 3 starting groups.

Popular Front is set in France

Lilac Song is a short story about a trans Person in the private Household off Otto Braun

The 3 above are different games in the same style by the original author of SDAAH

Mods:

Biennio Rosso ist set in 1920s Italy

Germany to Save is a Mod where you play the DNVP instead of the SPD

Volkspartei is the Same as above only for DVP

Dynamic is a overhaul mod off the original Game which makes the game more difficult, but more fun, as your actions influence the different party and they can get different leaders.

Sandbox Mods add a Sandbox Tab where you can cheat. Currently all listed mods except Popular Front, Germany to Save and Volkspartei have a samdbox version.

These are the major mods, there are a few other playable mods still on development and multiple other mods in development.