You get points for each found pair. For each next pair in a row you get extra points. The more pairs in row you find the more extra points you get.
You get extra points when you find the pair on the first try (the card of found pair was not opened in current game level). This bonus is adding to other points.
The number of points in quick game decreases with time.
Time indicator in challenge is only for informative purposes.
You get different number of points on different difficulty levels. The more difficult the level is, the more points you get.
The points gained on different difficulty levels are not equivalent.
You lose lives in challenge when you fail to find the certain number of pairs in a row. This number decreases as far as you open the pairs. This number depends on difficulty level.
If you find several pair in a row you can gain lives. The more difficult the level is the more pairs in a row you have to find.