Hopper is a genre all to itself.

It includes pretty much ALL genres of TTRPG.

In Hopper, you play a character based on yourself.  Chosen by Hopper Command to take the Trainee Exams, you are sent through Space, Time, and Probability.  ( Think of a combo of Stargate SG-1, Doctor Who, and Sliders ) At each IT (Infiniversal Transition) you and your team are given a mission to carry out.  You MUST complete your mission or you are stranded on the IT you landed on.  Your Hopper Tech benefits would slowly disappear and you would grow old and die there.  Complete your mission and you go on to the next IT mission and gain some upgrades to your body and equipment.

Eventually, you should reach Hop #21, at which point you are a full-fledged Hopper and no longer required to go on random Hops and complete missions.