Marathon > Doom
I remember when my pops brought home a shareware version of Marathon II from a buddy of his at work. . I was like "What game is it?" He just said, "You'll see." He loaded it up to our PowerPC and I double clicked on the Marathon II icon. "Marathon? This like Doom, dad?" "Its like Doom, but only better," simply replied. And he was right. My pops, my bro, and I played well into the night, it was fanstatic. Its one of the few games I actually remember my father getting hooked on, perhaps the only one. Oh well, it was good times.