• As we mentioned before, the game starts with your character's birth. After choosing what your character will look like at 19 (what, no age choice?), you get the "moving around" tutorial once you hit the age of 2. At the age of 10, you get the combat and game menu tutorial. At 16, you take a test to get bonuses to attributes you seem to best fit. At 19, you finally get to go out of the Vault to look for your missing daddy.
• Skill choices will be more important than ever. Choosing certain main skills can close off some quests entirely.
• The third-person combat view will be similar to the one used in Resident Evil 4
  
• Radiation is present almost everywhere in the world outside the Vault. You can regain health by consuming food, cola and water, but you should keep an eye on the rad level of these items, especially the water.
• Doctoring will once again play a big part in Fallout 3, as the broken bones and similar bodily harm you get during battles can only be healed by a doctor or by using a surgeon's kit. You should get these healed as soon as possible as they give you penalties such as not being able to run or getting a huge hit to your accuracy.
  

Via KILLZONE Unit