# Self-Learning Mechanism for Mobile Game Adjustment towards a Player
## 2 System Description  
_Wonderful Animals_ is a mobile game application developed for the Android platform using the Java programming language in Android Studio [26]. The mobile application consists of three different games: puzzles, a memory game and a spot-the-difference game. The main menu of the game presents all available games and their levels, which are shown after a player deploys the game. The game main menu is shown in Figure 1. The game interface is made to be very intuitive for users of all age categories. Android apps are event-driven; i.e., all interaction between the app and the user happens through events such as touching and swiping [27]. The app has been tested on different age categories and has been shown to be easy to use without confusing user interface elements.  
Puzzles are the first and main part of the game and they are grouped in four levels of complexity. Task complexity evaluation is based on the assumption that the more complex task that is connected with the higher probability that the task will be difficult to perform, and the mental effort and possibility of errors will increase [28]. The first level has five puzzles consisting of four pieces and they are shown in the first row of the main menu; the second level has 10 puzzles consisting of nine pieces (icons in the second and third row of the main menu); the third level contains 10 puzzles consisting of 16 pieces (icons in the fourth and the fifth row of the main menu); finally, the fourth level consists of five puzzles with 25 pieces each (icons shown in the sixth row of the main menu). When a player has tapped (chosen) one of the puzzles, pieces of that puzzle are shown on the screen. The player drags a piece of the puzzle to an outlined grid of the final picture. The player drops a piece of the puzzle into some segment of the grid and, if the placement of piece is correct, it stays shown as part of final picture. When the puzzle is completed, the player receives their completion time, shown on the screen. Every game level has a predefined time, which is limit for the player to complete the puzzle and receive the congratulation message \"Wonderful!!\". So, only the player who has finished the game level in less than the predefined time will receive the message \"Wonderful!!\".  
The second game in the application is a memory game. The memory game (find pairs or simply \"pairs\" in the application) is a game of matching pairs among many pictures, in particular matching pairs of animals. The success in this game depends on player memory and concentration. There are three levels of complexity: a level with 10 pairs,  
Figure 1: Main menu of the app _Wonderful Animals_.  
a level with 15 pairs, and finally, a level with 20 pairs. When a player starts, for example, the first level memory game, 20 grey squares are shown on the screen, hiding 10 pairs of animals that are randomly placed. The player chooses and taps two grey squares on the screen. Pictures of animals behind these two chosen squares are shown for a while. The player needs to memorize what pictures are behind them in order to match its pair. When all pairs are found, the player receives their level completion time, shown on the screen. Additionally, if the player was fast and successful (if he/she had finished the game level within less than the predefined time), they receive the message with the congratulation: \"Wonderful!!\".  
The third game is a game to find the difference (spot the difference). The player must find a requested number of differences between two otherwise identical images of animals. When a player spots a difference, he/she taps on it; if it is the correct position of difference, a ticked line is shown on the screen. When a player has found all the differences, a level completion time is shown, and as with the other two games, if they were fast in solving the task, a congratulation message \"Wonderful!!\" is shown on the screen. There are three levels of the game: images with three, four and five differences.