Thunder Rock is the huge chunk of brown rock sticking out of a flat desert - here's a reminder of what it looks like to start with

I decided to tackle this in stages, with a series of challenges, gradually lowering the level, working towards creating a lush oasis with a green hill:

Stage 1 - Achieving the objective and making some money to fund the next stage: the objective is easy for this scenario, you only have to get 900 guests and you are given 4 years to achieve it ... and since the top of the rock is reasonably large and reasonably flat, it's easy to plonk down a lot of rides with no regard for how it looks, creating a fun and functional park, but not particularly attractive ... so I didn't use any scenery or landscaping for the first stage, and soon had the 900 guests and lots of money.

Stage 2 - The Ring Road: There is a narrow strip of land which goes all the way round the rock, only about 3 squares wide, and my challenge here was to build rides and a path all the way round, with no branching, so the path had to directly touch each ride exit and each queue path ... there were a few corners where my path had to briefly go into the rock, to get around the 3x3 flat bed rides, but the path was mostly on view ... I managed to squeeze in quite a few rides, using the rock for some underground sections of track, including a water slide, a log flume, and four powered launch roller coasters, as well as several flat bed rides ... the great thing about this rock is that it is so easy to go in and out of the vertical walls.

Stage 3 - Clearing the top of the rock: after all that building it was satisfying and fun to demolish everything on top of the rock, especially since it wasn't very attractive in the first place ... I cleared all the rides and paths off the rock, and then had plenty of money to start a bit of land mashing.

Stage 4 - Reducing the height of the rock: at the start of the scenario, the rock is mostly around height level 23, with the highest peak at level 27, and I decided to divide it into 3 flat steps, with the front step being the lowest at level 18, and the back step being the highest at level 22 ... I spent almost all my money but the rides down below were generating more, so I had plenty of money to redevelop it.

Stage 5 - Redeveloping the top of the rock to make it fun and beautiful ... focusing on the top again, it's like working on two different parks, and it's important to assign mechanics to specific areas, either on top or down below, otherwise they can't find the rides, they have no concept of 3D and can't read maps. The rock is still very high, with plenty of room to build inside ... most of the rides inside the rock are from stations on the ground level, but there's a powered launch rollercoaster from the top level in there too ... all my powered launch rollerecoasters have sections which are visible above ground because I like seeing the trains come out of the wall :)

So here's the screenshot of the park after both the top and the ground level were developed.

Now I'm working on the ground level again - I totally cleared it, and raised the ground one height level, with a slope towards the park boundary so the land is contiguous with the surrounding landscape, and covered it in grass, to begin the transformation into a green hill ... now I'm building a new ring road ... I was a bit reluctant to destroy my water slide, but my new one is even better ... I've built a shuttle monorail which goes half way round the rock, from one side to the other, all out in the open - the journey takes 50 seconds ... and managed to squeeze in a wild mouse ride round the back.