What if the Earth's axis were tilted 90° to the ecliptic?
If the axial tilt of the Earth was 90 degrees most of the planet would have extreme seasons.
With a 90 degree axial title most of the two hemispheres would effectively be arctic conditions. The equator, tropics and arctic circle would all be at the same latitude. Summers would be months of perpetual daylight, Winters would be months of perpetual night.
Most of the Winter hemisphere would experience extremely cold temperatures and would be frozen.
Only about 4 million people live north of the arctic circle due to the extreme weather. With an ninety degree tilt only a narrow band around the equator would experience the 24 hour day and night cycle and reasonable changes in temperature.