The Focus Attack is what gives IV its strategic depth. It's what will cement the game's future as a tournament title. Triggered by pressing middle kick and middle punch at the same time, the Focus Attack is intended to be a single strike that absorbs an attack and stuns your opponent, perhaps setting them up for a multi-hit combo or a devastating, health bar clearing Ultra. There are three levels to the Focus: simply tapping the buttons will result in a weak Focus Attack, holding them for about a second then releasing when you see your character flash will result in a medium powered Focus Attack, and holding the buttons for about two-and-a-half seconds will result in an unblockable Focus Attack.
On the face of it the Focus Attack seems useless. It appears too slow and predictable to be an effective tool. But dig a little deeper, perhaps spend half-an-hour messing about with it in the practice mode, and you'll find it an indispensable and fun technique. Doing the Focus Attack as your opponent gets up, timed so the unblockable hit lands just at the right time, is incredibly satisfying. The Focus Attack can be used to "cancel" certain moves, too. Perform a dragon punch with Ryu, for example, which knocks your opponent into the air, then cancel the recovery part of the special move animation with the Focus Attack, then cancel the Focus with a dash (double tap forward) - this gives you just enough time to perform his multi-fireball Ultra so it hits your falling opponent. This is advanced play only the dedicated will be able to pull off, but for fighting game fans it's heaven. It makes Street Fighter IV feel new despite so much of it feeling familiar.
The Focus Attack is intertwined with the new Revenge Gauge. This gauge supplements the EX/Super meter by only filling when you take damage or when you absorb a hit with the Focus Attack. Once it's filled above halfway your spectacular Ultra move becomes available. The motion for this might be two fireballs and all three punches or a charge down back, down forward then down back and up forward and all three kicks. Either way, your Ultra is usually the most damaging move at your character's disposal, and because it only becomes available when you've had your ass kicked, last minute comebacks are a possibility in every round.
Despite the simplicity of this system, it's ground breaking for the Street Fighter series. Once you realise you can hit opponents with Ultras following a "Focus Attack Dash Cancel", once your brain readjusts to the fact that you can fill up the Revenge Gauge by absorbing projectiles from projectile-happy opponents, Street Fighter IV stops feeling weird, stops feeling slow, and becomes one of the greatest fighting games ever made.
Experimentation becomes a thrill. Experimenting with the four brand new characters, French Fei Long/Zangief hybrid Abel, American fatso Rufus, Mexican Lucha libre El Fuerte and secret agent Crimson Viper is as fun as it was with Ryu and Ken in the early 90s. Experimenting with all the secret characters, Fei Long, Cammy, Rose, Dan, Sakura, Gen, Rose, Akuma, boss Seth and Street Fighter débutante Gouken (Ryu and Ken's master and Akuma's brother) is just as fun. Simply messing about, marvelling at the Ultras, the throws, listening to the opponent specific lines of dialogue, it's just great for Street Fighter fans.
A special mention has to go out to the art style. Screen shots do not do the beauty of this game justice. Capcom's gone for a bright, brash cel-shaded look that sticks two fingers up at "next-gen" efforts at photorealism. It works brilliantly. The characters are more expressive than any seen in a fighter. Just before you catch your opponent with an Ultra, you see their eyes and mouths widen in horror as time slows and you charge up your hit. Punches almost force eyeballs to pop out of their sockets. Kicks to the stomach bend spines. Knock downs rock the eye-catching backgrounds. The violence here isn't bone-crunching gruesome, like Tekken, it's cartoon gorgeous.
Online play is, as expected, robust, the netcode performing on a similar level to that found in Super Street Fighter II Turbo HD Remix. On the whole it works in a basic, functional way, but Capcom has innovated by allowing other online players to interrupt your Arcade mode play and challenge you to ranked and player matches. Not only does it make playing the Arcade mode (and unlocking all the hidden characters) more interesting, but it gives the game a real arcade feel.