A preposition is a word or phrase that shows a relationship between 2 things in a sentence. For example the sentence "The book is on the shelf" contains 2 objects (book and shelf) and the preposition 'on' denotes a relationship between them. Other examples of preposition include 'under', 'by'. In this game, all the preposition used are prepositions of place which means that they describe where objects are in relation to other objects.