Ryu is the oldest of the old school street fighter characters. The first Street Fighter allowed you to play Ryu (player 1) and Ken (player two). I only remember that you could throw fireballs, I didn't have the manual dexterity at the time for dragon punches (although now, I've developed that
quite a bit). He had red hair too.
Street Fighter 2 came along, and he'd developed dark hair, and a new look. The original main character, a true fighter, always in search of a challenge, was back with Ken, and six other fighters, as people at arcades were treated to an extreme popularization of a genre which hadn't seen much light previously. People were invited to use their kung fu against each other, and Ryu had been there from the beginning.
Ryu has been in so many games (different incarnations of Capcom's big fat series) that it's almost not even funny. But it took until Super Street Fighter 2 for the programmers to finally differentiate Ken from Ryu. At this point, Ken received the flaming dragon punch, and Ryu received a fireball that could actually set people on fire. If you payed attention, Ken's whirlwind kick hit more times than Ryu's, which hit once, but for less damage with each strike. In the game that seemed like it would never be,Street Fighter 3, Ryu gained a new side kick move, and in Capcom vs. SNK, Ken received a really cute 'flip kick' move. But Ryu, the world warrior, the only character who has an 'evil' alternate from a bizarro dimension where he earned Akuma's power to have the Raging Demon Combo, is old school. He's so old school that it's amazing anyone would keep him around.
In every fighting game you play, there'll be a 'Ryu' clone. Trust me. Cyclops, Megaman, Morgan, Kyo, Ryo, the list goes on and on. Tekken players can shut up too, because F,D,DF coaxes a Dragon Punch out of Jin in Tekken 3, or Tag Tourney, and where do you think those quarter circle and half circle motions got their starts? Ryu from Street Fighter ONE! That's where.
I'm wondering if and when Capcom will retire Ryu to being the ass kicking old man character, but they probably never will. Ryu will stay the same age, from when I was 8, till I'm as old as him, and until I age far beyond him, continuing to play Ryu against young upstart arcade kids who think I'm being a cheap bitch, when in fact... I'm just a loyalist to this character.