Two responses in a row for your suggestions :O
This would be interesting to see. I have a few ideas of how someone could possibly make this.
Have it so when you fire, it has a relay-type shot thing that spawns an invisable target at where you are looking. After you do so, a rocket will be shot forward for a half second or so, then go up either straight or at an angle. Once the rocket reaches a certain height (straight up) or reaches the midpoint between the player and the desired target (up at an angle) it will then change direction and go towards the original target.
P.S. This is what a Javelin Rocket does, at least in CoD.
I'll post a badly drawn gif of what I mean in a second o.OHere it is:

Red = Javelin
Yellow = Target
Green = Midpoint
Blue = Projectile
Frame 1: Blocklander clicks where the want the javelin rocket to land.
Frame 2: Rocket comes out of the javelin.
Frame 3: After a very short period of time (1/2 second) rocket goes up at an angle.
Frame 4: Rocket hits the midpoint (the middle of the player and the target).
Frame 5: Rocket descends at an angle towards the target.
Frame 6: Rocket hits target.
This should make it clear of what the Javelin should do.