The knife needs fixing, it does not always hit all of th handies in its radius and it seems that some handies are killed when they are not in range ( im guessing the white slash is the range).
more weapons, more areas, and a story to it. suggestions for some weapons, moltovs (causes damage over time), rpg (unlikely but it would be cool to have some thing like that), and a veriaty of pistols, assualt rifles, smg, and light machine guns.
Add unlockable characters (frogger lol), more cars, themes (like space, wild west [jumping from horse to horse] 80's, 90', candy), sandbox mode, story mode (your late for some thing or some things on sell that you really want so badly the you jump from car to to try and get there).
A sandbox mode would be nice, were you have unlimited money, both bases have infinite health, and you can build on both bases so you can control what the enemy has, and the option to change the weather.
What if you were to increase the max grade to 40, 45, or, 50 and have it so at grade 20, 25, or 30 that there is a another class. Make it so that it branches of into three other classes, also have it so it's also depends on stats and there current class, because what I notice is that a student that had strength the highest at grade 10 may have dexterity the highest at grade 30 (I suggest to make the stats have that change more often if you want to add my idea).
The graphics are nice and I like it that you can upgrade the lights and engine on the sub. I think its cool that you have to return to the surface to cash in ever. I think it needs a bit of a challenge to it like adding Health for the sub and have some marine life that can damage it.
There should be a limit to how many misses in a row because it pisses me of a hello of a ton. I think a maximum of 3 misses in a row should be the limit.