formal if you engage on a particular activity, you do itusually passive
So what projects are you engaged on at present?
phraseengage on !Engage upon is more formal than engage on and is mostly used in writing. be engaged on/upon sthBrE formal if you are engaged on a particular type or piece of work, that is what you are doing at the time: During the war Richards was engaged on work of a secret nature.The chairman, Ed Borkovsky, is currently engaged on a European tour to promote the conference.