Four types of sensory inputs available. "Sight" is missing as the game occurs entirely in darkness or rather the bodies have no occular organs. This is a design choice to make the base game compatible with non-sight based design. Partly this is to reduce the descriptive load for builders and players. As they say, a picture costs a thousand words. In a text interface that is expensive. If we therefore remove "pictures" from the virtual environment we save thousands of words.
Scent and sound operate at range. Scent is the most difficult to hide but conveys little positional information. Sound is easier to control or repress but gives away one's position with significant accuracy. Scent is most used for signals (some involuntary), sound is useful for signals and messages. Touch is obviously a highly intimate form of communication. Taste, can convey irrevocable information and cannot deceive perhaps.