What it says on the tin.
OTL Ernst Röhm was one of the most senior Nazi's, and possibly the closest to Hitler himself (for example, he was the only one to call him "Adolf" instead of "mein Fuhrer"). Of course, once Hitler ascended to the Chancellery and Röhm started talking up a "Second Revolution", he was marginalized and liquidated during the Night of the Long Knives.
So, using any POD after January 5th, 1931 (when Röhm became the head of the SA), have him, not Hitler, become the leader of Germany. What does a Röhm lead Third Reich look like? Could Röhm even have stayed in power? If WW2 kicks off, how does Röhm fare?