Easy game, don't bother playing liberal instead prep for the inevitable civil war:

Nab the interior ministry and anything else defence related, militarise the reichsbanner, purge rightists in reichswehr and police, ally with communists, shore up union support, form the iron front (but swerve it away from anti-communism), and just coup Hitler the moment he takes office. The most useful foreign relations thing you can do is training with Austrian socialists (no anarchists nor USSR for some reason). When the civil war popped off I had the police and military helping the communists crush nazi skull while the unions' general strike paralysed the state.

The game seems to treat this as the worst out of potential ways to prevent Nazi Germany which is cringe on its half.