In recent years it seems many games have incorporated some version of a 'Horde' mode, a wave based game mode that gained a lot of attention I believe mostly due to it's inclusion in Gears of War 2. The list of games is long. Modern Warfare 3, Uncharted 3, Lord of the Rings: War in the North. The list goes on. One feature that is used but seldom so is the 'New Game +'. Probably remembered mostly from the Resident Evil series it is a mode that allows the player to play through the campaign again after completing it while retaining weapons and experience. The items or skills retained depends on the game. In games like Resident Evil 4 you will retain everything but in a game like Dark Souls you will retain level and skills along with all your items save certain 'key' items, such as keys and other progress important items.
A few games have had them in the past years such as Demon's Souls, Dark Souls and Mass Effect 2 but I'd like to see this feature used more widely through the market, to an extent of course as to not overkill it. Most of the New Game +'s have you replay the game on the same difficulty with the exception of Dark Souls and Demon's Souls where the difficulty goes up after each successive New Game +. With the rise in difficulty, however, comes reward. More souls for your troubles. Although this could be seen as a balancing to the game as the more souls you pour into leveling your character the higher the cost to level the next time gets.
With that said I'd like studios to start getting creative with this mode. It would be nice to see a linear and otherwise boring game like Call of Duty (campaign) be spiced up by adding some cool features every time you beat a New Game +. Maybe each time make it harder, sometimes at certain firefights add more enemies or a heavy enemy or something the player wasn't expecting each time around just to keep it fresh. Every time you complete the game you could unlock something cool. It could be anything ranging from red dot sights on all the weapons you pick up to taking a tip from Halo and having the hidden language mod or confetti headshots. They could even go the way of Resident Evil 3's Mercenaries Mode and add in a point system where they faster you complete the campaign or set trials, the more points you get to unlock stuff like cool weapons or infinite ammo. In this day in age almost every game has some sort of multiplayer feature be it coop or full on competitive modes it has become a must. With this sort of innovation they could easily add some fresh air to a game's campaign and give it at least a couple more hours of play. Leave your thoughts or ideas.