Knowing the intent of a search query allows for more intelligent ways of retrieving relevant search results. Most of the recent work on automatic detection of query intent uses supervised learning methods that require a substantial amount of labeled data; manually collecting such data is often time-consuming and costly. Human computation is an active research area that includes studies of how to build online games that people enjoy playing, while in the process providing the system with useful data. In this work, we present the design principles behind a new game called Intentions, which aims to collect data about the intent behind search queries. Keywords Human Computation Game, Query Classification, Query Intent, Web Search ACM Classification Keywords H5.m. Information interfaces and presentation (e.g., HCI): Miscellaneous.