F* Missiles Chasing Me - With Math

I DON'T KNOW IF ANYONE HAS DONE THAT BEFORE ! IF SO, DON'T ACCUSE ME OF STEALİNG.

Firstly, I designed this game without math sometime ago. Then I came up with an idea "games with questions" for this game it's "games with math. Anyway then I developed it by adding a random math question system and changing game play little bit.
If you wanna make this kind of games, visit scenerio web site (it's actually a blog post) to see some suggestions.

the Game :
Purpose of the game is to run away from intelligent missiles which chase you to damage but you have to answer simple math questions correctly and quickly in order to get some fuel.

Controls :
W > Move
A > Turn right
D > Turn left
Space > Use turbo, (more fuel)

Left arrow > Select A-)
Up arrow > Select B-)
Right arrow > Select C-)

Questin and Answer Logic :
When a new question appeared, first arrow key that you pressed is considered as your answer. If it is correct while new question is being created, you get some fuel.

Please READ This :
I don't really test the game to set optimum staff frequencies,time limits and actually all limits of the game.
Like;
>Frequency of Firing Missile
>Surviving Time Limit to Win
>Fuel Bar Limit and Begining Fuel
>Frequency of Asking New Question.

That's why I need you to play game help me reset these things. After making game better and more developed, I'll share the source.