Vire said:
As you said - improve the graphics significantly.
Change the structure of the single player - make it less linear. Have open expanses to fight in rather than narrow hallway after hallway.
Add Co-Op to the campaign.
Add in destructible environments.
Have meaningful vehicle combat in single player or multiplayer. (Maybe a new mode with vehicles in it.) Keeping all the classic playlists in tact.
Make headshots a more important part of the game. I feel like if you shoot someone in the foot for half a second they die regardless of skill.
Any of these things would have went a long way to making things feel fresh again in the COD format.
If better graphics or destructable environments means the game isn't 60fps, then I think a lot of people would have a problem with that decision. Vehicles....not sure many COD fans want that. Even if there was a separate mode for that I think most people would rather that energy go into spec ops, maps, etc. Vehicles means maps designed for vehicle integration, and Activision/IW probably think if people want to drive vehicles in a FPS they'll play BF3. And campaign co-op...isn't that where specs ops comes into play?
Assuming that IW/Activision only had so much time and resources to put into the game, I think COD fans (me included) are fine with them refining the game (e.g. new weapons, new killstreaks, weapon balancing), creating new maps, etc rather than trying to reinvent the series.
Can't fault you for feeling like all this is them guitar heroing the game. As someone else said, we've had a new COD game every year since 05.