# Game Logic In Rust This step implements the rules of the game in Rust as well. Slint's general philosophy is that you implement the user interface in Slint and the business logic in your favorite programming language. The game rules enforce that at most two tiles have their curtain open. If the tiles match, then the game considers them solved and they remain open. Otherwise, the game waits briefly so the player can memorize the location of the icons, and then closes the curtains again. Add the following code inside the MainWindow component to signal to the Rust code when the user clicks on a tile. ```slint {{#include main_game_logic_in_rust.rs:mainwindow_interface}} ``` This change adds a way for the MainWindow to call to the Rust code that it should check if a player has solved a pair of tiles. The Rust code needs an additional property to toggle to disable further tile interaction, to prevent the player from opening more tiles than allowed. No cheating allowed! The last change to the code is to act when the MemoryTile signals that a player clicked it. Add the following handler in MainWindow: ```slint {{#include main_game_logic_in_rust.rs:tile_click_logic}} ``` On the Rust side, you can now add a handler to the `check_if_pair_solved` callback, that checks if a player opened two tiles. If they match, the code sets the `solved` property to true in the model. If they don't match, start a timer that closes the tiles after one second. While the timer is running, disable every tile so a player can't click anything during this time. Add this code before the `main_window.run().unwrap();` call: ```rust,noplayground {{#include main_game_logic_in_rust.rs:game_logic}} ``` The code uses a [Weak](https://slint.dev/docs/rust/slint/struct.Weak) pointer of the `main_window`. This is important because capturing a copy of the `main_window` itself within the callback handler would result in circular ownership. The `MainWindow` owns the callback handler, which itself owns a reference to the `MainWindow`, which must be weak instead of strong to avoid a memory leak. These were the last changes and running the code opens a window that allows a player to play the game by the rules.