...looking for a camera that is good to capture large sceneries in town or nature, ...

For most people, this translate to having a wide or possibly an ultrawide lens. If the camera has a fixed lens (i.e., one attached to the camera that you can't remove and replace with a different lens), then the specification you'll want to look at is the lens's focal length. If the lens zooms (i.e., can change focal length), then you're most concerned with the lowest number in the focal length range.

Most folks would consider 24mm equivalency (i.e., something that yields the same field of view as a 24mm lens would on a 35mm (or 135 format) film camera) decent for landscape and cityscape shooting. (See the Nikon lens simulator to get a sense of what different focal length equivalencies can mean. FX is 135 format (1x crop), DX is APS-C (1.5x crop), and CX is 1"-format (2.7x crop).

With an interchangeable lens camera, you can go much wider if you like by purchasing a lens that does so, but most of the interchangeable lens cameras may be outside your budget for the simple reason that you have to buy not only the camera, but also the lenses.

... also at night, ...

Here, you're probably going to be happier with a camera that has a lens with a maximum aperture of f/2.8 or wider (smaller f-number), and a larger sensor (say, 1"-format or larger; see the Wikipedia entry on sensor size). Both of these factors make for better low-light photography, particularly if you are handholding.

However, if your night photography is of an unmoving subject, and you can use a tripod, neither factor is necessarily required. Instead, the specification for fixed lens cameras to look at here, would be the maximum shutter speed allowed. The longer the better for night photography, and many compact cameras may max out around 15 seconds or less. Interchangeable lens cameras often have a "bulb" mode, which means the only limit on how long the shutter can be open is the life of the battery in the camera.

... and provides enough possibilities for individual settings especially concerning light and colour nuances.

This generally means having full control over the exposure settings of the camera. This generally translate to having the so-called "PSAM modes":

• P, Programmable Auto, an automatic exposure mode that still lets you adjust some settings, such as ISO and white balance, manually.

• S, Shutter Priority, where you can set an explicit shutter speed to use, and the camera automatically chooses the aperture (and possibly the ISO).

• A, Aperture Priority, where you set an explicit aperture setting, and the camera automatically chooses the shutter speed (and possibly the ISO).

• M, Manual, where you choose and set iso, aperture, and shutter speed explicitly.

Color, however, may be a matter of white balance, or post-production settings and adjustments, more than a matter of in-camera settings, if you shoot RAW.

It should be something that guarantees me to be content with on the long-term...

The problem with this thinking is that cameras are digital these days. How long are you happy with any digital device? How often do you upgrade your phones or your computers? A digital camera body can be like that--it can seem outdated, or you can decide you want newer features relatively quickly. These are not like film-era cameras that could last you decades.

I am willing to spend up to 600$ for something that is really good, but am rather thinking of something around 200-400$...

This is your single largest limitation. A good basic interchangeable lens camera setup, if you purchase new, is liable to cost more in the US$1500-$2000 range. You can start low, or you can purchase used, but that, to me, is the ballpark figure for a good basic setup of a body, two or three lenses, and accessories like cards, batteries, a bag, and maybe a tripod or flash. Not to mention post-processing software.

With your budget, I'd actually say a fixed-lens camera, preferably one with a larger sensor, if you can find it used, might be your best bet. A previous-generation Sony RX100 or a Canon Powershot G1X or something.