The GIS program can represent vector layers over background of raster data in different modalities, mainly as Digital Elevation Models (DEM) or topography. Typical rendering of the program is hill-shaded relief expressed by color mapping from altitudes, in accordance with provided legend. Also the legend and rendering can serve for Earth ecosystems, albedo of Moon and other kinds of scientific data. Also users can see water resources of Earth over the raster data and labels of features for Moon and planets.
Main features of the program include: multitude of navigation options, vector object identification, querying vector record of interest, instant fine game with altitude-to-color mapping, instant Sun illumination modeling and more.
Some space on disk should be reserved for offline data collections thyself. For currently existed collections 27GB will be enough, but better if you have more. Also you can have less for case of using only particular collections. You can look at maps catalog on site of developer for identify data collections for required maps and their size.
Primary design of the product directed for exploring big amount of spatial data, such as global coverage with any desired level of details with high speed of operation over the data from side of user. The design optimized for using multi-resolution hierarchical and compressed data collections, permitting less disk space consuming and having random access to content, reflected in high performance. Also comprehensive overlapping policy for labels exists, against overcrowding.