In the series so far, mowing down pedestrians has always been one of the great joys of the Grand Theft Auto franchise. The violent crush on impact, the blood splatter, the exquisite screams, and the thrill of an instant getaway that only a hit and run can provide. And usually, slamming a pedestrian with a car would instantly turn their body into a ragdoll sliding over your car. Fun? Yes. Realistic? Not so much. GTAIV’s new Euphoria system (licensed from NaturalMotion) adds in some very clever AI which makes the hit-and-run victim move their body in the same way a real person would. Upon impact with your car, they attempt to regain their balance and stop themselves getting too hurt, with realistic movements like flailing arms. The animations are fluid and each one feels unique, resulting in an effect that ensures hit-and-runs are always entertaining even after the story missions have started to drag. Euphoria also plays a more subtle part in a lot of the character animations. The way that characters react to falling down stairs or off rooftops, or being shot or blown up, have all been enhanced with extra lifelike movements. It truly comes into its own when Niko and friends are drunk upon leaving one of the in-game bars, as they amusingly stumble and try to keep their balance as they walk. It’s a significant step up for dynamic character animation and hopefully more games will begin adopting the system themselves (sports games in particular would find a lot of value in this).
A notable new feature is the in-game mobile phone, inspired from Saints Row (which was itself more than a little inspired by the GTA series). It can be used to contact Niko’s friends and bosses during missions, re-attempt failed missions, and can also be used to start up the online multiplayer features of GTAIV. The phone also provides the framework for Nikos virtual pals to persistently call up and ask him to take them out on a date. It’s a shame that Rockstar never implemented a way to cut off these nuisance callers with a swift “f**k off and die” remark, which perhaps would have made the whole thing worthwhile.
Liberty City is now lit with a very impressive lighting and weather model which provides a variety of different moods to the city depending on the time of day and the conditions. A mixture of post-processing filters occasionally add a blue or orange tint to the graphics, and HDR lighting effectively mimics light sources without being overused. The lighting, weather and excellent draw distance all work together to make most locations look stunning throughout. The lack of a built-in camera mode similar to the one provided in San Andreas is a sad oversight, as it would have gone hand in hand with the new high resolution Liberty City and its vivid lighting system.

Not only had Niko forgotten to turn the oven off before leaving the house, he’d also forgotten to leave it in the kitchen.