The local authority won't allow you to build above tree height in this park.
At first glance, it looks like the height restriction's the only challenge in Harmonic Hills, but players will realize as soon as they attempt any construction or landscaping project, that there's far more than just the height restriction to overcome. On the bright side, marketing campaigns are still allowed.
Scenario Guide[]
A scenario guide for Harmonic Hills' particular challenges, can be found here.