The first step in designing an environment for a level is deciding the setting. Based upon the concept of my game the details would be Ancient Egyptian but I can’t decide whether to have a desert setting (traditional, and boring) or have an overgrown look ( either tropical, or European). The latter would be more interesting as a concept. It would show a familiar landscape in a wholly new, and unexpected setting.
To be safe I will plan both. My first, the one I will create, will be the overgrown. The second, my reserve, will be the traditional Egyptian backdrop.
As the overall theme is concurrent with both designs it will be plainly Egyptian:

Both scenes will also have a water source, a river, with settlements on it’s banks:

Moving on to the first landscape.
As I said it will be laden with millennia of overgrowth. So trees will be all over, with pathways, trampled by the indigenous people, running between settlements, temples, waterways, etc…
The feel of the forest would need to feel slightly claustrophobic, especially on the pathways and certain intersection areas. With foliage encroaching upon the ancient structures themselves.
This is the kind of general density I am aiming for. Some places will be more impenetrable, and some more open.

Within the forest will of course be the ancient structures. They will sometimes be obvious, you can’t hide a pyramid behind a bush, sometimes less so. This will add a feeling of realism to the scene. Having many of a cultures relics seemingly scattered amidst a new terrain. I envisage something like this:
In addition there will be a contrasting area where the current occupant will have kept the area around their home trimmed and well maintained, either in homage to an old tradition, or just plainly fussy. This pic is how I see a small corner of the landscape ( minus the modern furniture):

The second incarnation of my idea requires more work on lesser details. The landscape is primarily sand, so that is dull and repetitive. The only variation would be in the smattering of bushes and rocks, or some special rock features.
This shows how sparse a desert is ( hence the name). With little room to explore any real placing of overgrowth. Plants only grow where there is water, so it would be patchy at best.

This shows the interesting rock features found in desert’s. How the sand carried on the wind has carved stone monoliths over the centuries. Anther example, in a different way, is shown below:

Though these are interesting they are limited in their design and scope, I guess as much as a desert would be.
One final interesting thing I am playing with is to incorporate some snow, into either:

I feel this adds a spectacular twist to both formats. Maybe a hidden path leading up to an area like this.