The most important aspect of the new engine to me is the lighting/shadows. Nothing else (graphically speaking, not talking design here) has as much impact on what a game feels like visually than good lighting and shadows.
Warm colored light early in the morning and colder bluish light in the evening/night and individual lightsources and the sun casting shadows and such. This to me is 90% of what the new engine offers. The last 10% being better foliage (grass/trees) and higher polygon characters.
Now we need an ingame radio. A radio that is located inside RK missions (on desks/tables), that people also can buy from a shop and put in their apartments and so on. The music on this radio will be music made/recorded by players and sent to FC. FC will put the music in the game but only on radios, so only people near a radio can hear it. What music is played depends on where the radio is and is chosen by FC.
So some players that are good with electronica and such can make music that can be heard in main omni city locations or in bars or clubs. People that play classical guitar or piano or whatever can have their music be heard on radios in apartments and such. Radios can be turned on and off and the volume depends on how close to the radio you are standing. Song-library will run on a loop.
The music can be original created work or can be covers of various well known songs. Froobs have access to this content as well so its free and no one is making any money on anything in hopes that this wont attract lawsuits. Anything sent to FC that is original created work, automatically grants FC ownership of that work so once its sent, no one except FC can claim ownership of it
I know I'm talking partially out of my arse here because something like this will probably never be implemented. I just think it's fun to think about and talk about
I know we got some talented musicians here and it would be fun to have some fun with that and add some musical variation to the game since all ingame music is so old by now. Most people I know play AO with the sound turned off, which is a shame, yet perfectly understandable.