lol... its not about howto control your character, its about knowing what the games about.
even if it is a simple explaination like, sure some game like Space invaders and pong are obvious ... but others will like a little introduction on what they're about to download.
Half-Life is an excellent example for this because back in '96 whe i first heard about it, i though "pah, another crappy Quake2 clone" but then more and more was said about it ... although the engine features kinda flew over my head, the story itself compelled me to want it.
FPS up until the had been mindless shooting with very little in the way of a real story and more about just placeing you in an environment with things to kill.
Half-Life's story set it apart from thousands of clones, particularly the ability to talk to people and have them help you like and RPG