I think it would be nice to have a better training mode: it can be hard to master basic weaponry (bazooka and grenades) considering forces, winds and so on.
So, why not helping the user with trajectories? In a "training mode" (or easy mode or anything you like), trajectories becomes visible. It's hard to explain it with words, i hope you understand the images:
Hope you're interested... Because I really suck with grenades!!