A new additional system implemented in Tom Clancy's Rainbow Six: Vegas 2 is the Advanced Combat Enhancement and Specialization or ACES, where players will be rewarded with different weapons based on tactics used in the game.
The ACES system is divided into three parts: Marksmanship, Assault, and Close-Quarter Battle (CQB).
Nearly every single kill the player makes is organized into one of these three categories and scored based upon how the kill was performed (i.e., a headshot would count towards Marksmanship, or shooting through a wall would count towards Assault, or killing an enemy while blinded by a flashbang would count towards CQB).
By getting a high enough score in a category, the player unlocks a specific item for that category; for example, the Assault category might reward the player with a new type of assault rifle, while the Marksmanship category might reward the player with a new type of sniper rifle. Even though the ACES system goes across modes there are certain rewards that can only be unlocked in single or multiplayer (reference: Media Broadcast).
Kills are only worth one ACES bonus, with certain bonuses taking priority over others - for instance, killing an enemy from behind at short range will only give three CQB points rather than six for both conditions, while a long-range kill on a turret gunner will count for Marksman but not Assault.
Points can be gained in all game modes present in the game - Story (Singleplayer and Cooperative), Terrorist Hunt (Singleplayer and Cooperative) and Multiplayer.
|Kill an enemy or player with explosives (anything other than C4)|
|Kill a shielded enemy or player|
|Kill an enemy or player using a turret gun|
|Kill an enemy or player with C4|
|Kill an enemy or player through cover|