This is a summary of the features, from the offical website :
- 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 related debuffs.
- 25 weapons, 2 different shooting modes (auto/semi), dynamic precision (moving/shooting/standing worsens accuracy), drilling shots, iron sighting, extended zoom scopes.
- Complete hacking system with game play impact Hacking minigame. 9 devastatingly subtle PSI powers.
- About 20 NPC with non-scripted, fully reactive and efficient AI, endowed with a sense of initiative bots. Bloody close combat with technical detail. Incredible physical movement realism thanks to Source Engine physics.
- Excellent 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.
For more details about those features, use the menu.