Blokus family game

Blokus is a family game with four players and a 20 x 20 square board. Like chess or checkers, this is a game where you can see your opponent's pieces at all times.
rule：
Each player starts with 21 pieces: 1 one domino, 1 domino, 2 three dominoes, 5 four dominoes, and 12 five dominoes. It might remind you of Tetris multiminoes...
"For the first round, I have to place a pawn so that it touches a corner of the board"
"Next, a piece has to be placed so that it touches a corner of my own piece. It may touch a few corners, but never any side/side of my piece!
The game has a nice and natural user interface: just drag and drop pieces with your finger. Rotate the same piece. And long press to go back one piece.
"If no more pieces can be placed, it's my turn."
The game ends when every player has passed. "My score is: plus the squares of the pieces I placed".
You can safely quit at any time: your current game will be restored the next time you start it.
You play against machines. You can configure the corresponding artificial intelligence level: 4 levels.
You can only disable AI for human play.
After installation, you can play it offline.