* The multiplayer, teamplay, co-op modes directly influence solo play, 
  and vice-versa. The limits of solo and multiplayer games are finally 
  left behind. 
* Psychological and mental traumas management. 
* 25 weapons, different shooting modes, dynamic precision, drilling shots,
  iron sighting, extended zoom. 
* Complete hacking system with game play impact. 5 devastatingly subtle 
  PSI powers. 
* About 20 NPC with non-scripted, fully reactive and efficient AI, endowed 
  with a sense of initiative. Bloody close combat with technical detail. 
  Incredible physical movement realism thanks to Source Engine physics. 
* Total replayability due to primary and secondary missions, dynamic 
  environments, non-linear level progression, and random NPC spawn, type
  and appearance. Death doesn't penalize players: no need to restart the
  current mission. 
* Open-level gameplay for hours of play without reloading.