virtual – adj. existing or occurring on computers or on the Internet

plausible – adj. possibly true : believable or realistic

transaction – n. a business deal : an occurrence in which goods, services, or money are passed from one person, account, etc., to another

puzzle – n. a question or problem that requires thought, skill, or cleverness to be answered or solved

reward – n. money or another kind of payment that is given or received for something that has been done or that is offered for something that might be done

cryptocurrency – n. a kind of virtual currency or money

digital – adj. relating to computer technology, especially the internet