The sense of smell, olfaction, is rarely used in digital interactive systems, but, supported by the proper technology, olfaction might open up new interaction domains. Human olfactory experience involves active exploration, directed sniffing and nuanced judgements about odor identity, concentrations and blends, yet most olfactometers are not designed to study these aspects. We present a novel, compact and low-cost olfactometer fitted to the hand controller of the HTC Vive Virtual Reality (VR) system that employs stepless valves to enable control of scent magnitude and blending. Our olfactometer allows for concealed (i.e., unknown to the user) combinations of odors with virtual objects and contexts, making it well suited to applications involving active sniffing and interrogation of objects in virtual space for recreational, scientific, or therapeutic functions. Validation experiments involve gas sensor measurements and a smell training game in a “virtual wine cellar” where participants pick up and smell wine glasses. Results of the gas sensor study demonstrate precise and consistent scent output over extended periods of use. Results from a pilot study with a single normosmic participant using the smell training game for 2h daily over 28 days indicated dramatically increased performance in odor discrimination, identification and naming. An additional study of 12 novice participants provided insights into the usability characteristics of the olfactometer. In sum, our compact, low-cost olfactometer for virtual reality applications is sufficiently robust and exact to enable use in research experiments and game applications, developing expertise, and other olfactory interactions. Our olfactometer enables new forms of multisensory olfactory research where participants interact directly with odorous objects in VR environments. The research was funded by the Marcus and Marianne Wallenberg Foundation (MMW 2014:0178) to J.K.O and S.N.