The Space Quest series come from a time in my childhood when PC gaming was largley defined by the adventure. Sierra was the undisputed king of adventure gaming, with such golden franchises as Leisure Suit Larry, King's Quest, Quest for Glory, and yes, Space Quest. Space Quest takes Sierra's noted goofy humor to an all new level, and creates fun, engaging game play.
You play a janitor, who through sheer laziness, incompetence and dumb luck manages to foil the villains in every game. Thus, the gameplay requires you to work and think like a janitor. You have paltry tools, and weird items that you must constantly use in creative ways to solve impossible problems and ridiculous odds. You rarely get to shoot back and the gun toting thugs trying to vaporize you. You'll by doing a lot of typing on the first two, but the games gradually advances to a more intuitive point and click interface. Make no mistake, however, these games are hard. Those who have played through them a thousand times may have forgotten how unforgiving the early adventure games were.
Space Quest, however, is rewarding for all its difficulty. It dishes out ridiculous humor, goofy aliens, and slapstick regularly, and is definitely worth your time whether you want to relive the glory days, or take a trip the mists of gaming time.