Additive.

What is 3+2? Sounds easy right?.

Now 4+3 is it 7 or 6 ? Again easy, yeah?

What if you have to answer with 2 seconds or else it is game over? Not as easy as you think.

Additive is all about checking if the sum is right or wrong with right/left swipes . The longer you go without wronging, the bigger your score.

(The rumour is that if you get a score above 100 your IQ is over the roof).