The challenges give you the chance to face the player you choose. You will be able to challenge players in the maps you have played at least once, but remember it will be the score of the last game you played in that map the one that your rivals will have to surpass. You can pick your opponent among the players that appear in the ranking of the map. Similarly, every time you finish a game you will have the option to challenge other players. Once you challenge someone, we will send a message to the other player with your score and a link to the game you have challenged him/her, and we will invite that player to surpass your score.

The scoring system that it is used in Didactalia's challenges is based on ELO rating system which it is used in games like chess. This method is useful to calculate the relative skill levels of the players that compete against each other: - The player with more points, i.e. better global position, will lose more points if he/she loose, and he/she will obtain less points even if he/she wins. - The player with fewer points, therefore a worst global position, will lose less points if he/she losses, but he/she will obtain more points if he/she wins.

They are the points you win or lose when you accept a challenge. These points will be added or substracted from your total scoring. For instance, if you obtain 140 points in a challenge game that has a bonus of +100/-20, you will obtain 240 points if you win, but only 120 if you lose.