More weapons are available this time around.
Another major shift is the addition of unlockable weapons and a small amount of customization. As long as I can remember, Sam has had access to a very limited amount of guns - on rare occassion he was given something different to use, but the choice was never the player's. In Conviction, players have access to an impressive array of guns, both as Sam Fisher and as Archer or Kestrel (in the co-op modes). Any time you pick up a gun it's automatically unlocked for your weapons cache, which is available at certain checkpoints in the single player and co-op campaigns. Once unlocked, you can upgrade a weapon up to three times - up to two times for your grenades and mines - to either cause more damage, increase the range, increase accuracy, or add a "Mark and Execute" target. Not every weapon has access to the same upgrades, and you can unequip any of them at the weapons cache. It's not the most versatile customization, but it's much more than we had before.
Different uniforms are also available, and each can be upgraded up to nine times (added equipment slots, added ammo slots, or added armor), but only three upgrades can be equipped simultaneously. Some of the uniforms also have different patterns available. There are enough combinations for you to find one that you really like, and therefore feel like you have a fairly unique persona online. Ubisoft is promising new free downloadable content every week...I can see new uniforms and weapons as being the main focus for this.
Last Known Position is a great new feature that gives operatives an edge in co-op and single player.
The "Mark and Execute" and "Last Known Position" were probably the most talked-about new features pre release, and for good reason: not only are they unique, but they are effective. Performing a melee attack will fill your Mark and Execute meter, giving you the ability to wipe out multiple targets at the press of a button. This may sound like a gimmick that could potentially make the gameplay too easy, but in my experience it just added a tactical advantage when you're outnumbered. Keep in mind that five bogies in one room - all with automatic weapons or shotguns - is not uncommon in this game. You can actually Mark your targets before your Mark and Execute ability is available; perform a melee on some hapless target, and your Marks turn from gray to red. It's a sweet way to clear a room, and provides many heart-pounding moments of satisfaction. "Last Known Position" is a ghost-like image that shows you where and how the enemy last saw you. It works great, letting you literally play cat-and-mouse with bad guys (pardon the overused figure of speech).