In short - Its very good (6.5)
You got yourself a nice game!
however, IMO there are a couple things that should be changed so you get the most out of it...
1) Personally I dont think that the backgrounds worked too well... maybe you should try making the actual mini games fill the screen and then a transition going to the next 1 and so on?
2) Although many people might make the link between this and Grid 16, four second fury in concept, the fact that you have used new ideas and minigame makes this original... Just be careful when updating not too make it too similar or people who don't understand tributes might have a go at you :l
3) Make it more obvious that the speed is changing similar to what grid 16 does, it comes up and tells you... just have some sort of message...
4) I dont think the math game works properly...
on 2 occasions all 3 answers were right... :l Have a look at the code maybe? Try using if statements on the first box saying a random number then make box 2 look at box 1 and say if "box1"=true (true = correct answer) then display random number and the same for third box. If false then right answer displayed etc... I'm not too sure on the code here xD
5) Make changing backgrounds easier, I had no time to click the arrows make the keyboard numbers change the BG's eg. 1 = background 1 etc.
6) Music options and mutes
7) Try upgrading the graphics on the games a lil
8) on the laser game make the lasers stay there after they have been shot so it makes it devilishly hard xD
At least consider making these changes and you may improve your game a lot ^^
I would be happy to help with coding and art work if you wouldn't mind mentioning my name in the credits... :D
Drop me a line if you want to on - hi5er_@hotmail.com
hope this helps and good luck ^^
~Hi5er (Bob)