Press left and right arrow to move
Press spacebar to shoot
You can upgrade your bullets, moving speed, and shooting delay in upgrade step.
The upgrade step would be displayed by the score going up.
In upgrade steps, you can see three numbers like roulette, press spacebar to stop each number.
If you get numbers in line, like(1,2,3) or (4,5,6) etc, you can get 2 of better options. If you get numbers all the same, like(1,1,1) or (5,5,5) etc, you can get 3 of best options. Otherwise you get only one options.
An enemy is spawned in a second.