Following his humorous adventures in Space Quest III: The Pirates of Pestulon, Roger Wilco is relaxing at his favorite pub somewhere in time and space when heavily armed soldiers enter the room. Carrying a parting message from Roger's old nemesis, Sludge Vohaul, they plan to get rid of the janitorial hero, execution style. That is until a man with an over-sized hair dryer helps Roger escape through a time rip into the future.. Now Roger Wilco has woken up on his home planet, sometime in Space Quest XII. The series has gone to ruin without it's hero, Vohaul rules all.. Roger must quickly hotwire a time pod and undo Vohaul's plot. The most logical way to do this is to run amok through past, future and the end of the universe, having a few laughs along the way. If there's a few spare moments, he might swing by the galaxy's biggest mall, charm his ex-girlfriend whom he knows nothing about and provoke some brawly monochrome bikers living in the original graphics of Space Quest I.
Space Quest IV is the first in the Space Quest series to feature Sierra's SCI interface (better known as "VGA icons"). Sierra's standard icon set, used here, includes icons for Walking, Looking, Using/Pickup, Smelling, Tasting as well as inventory access. Roger Wilco is shown on the screen from the exterior in multiple viewpoints.