diff --git a/src/game_data.rs b/src/game_data.rs
index 629cf43..829f3bb 100644
--- a/src/game_data.rs
+++ b/src/game_data.rs
@@ -16,6 +16,7 @@ pub struct GameData {
     pub show_ghost: bool,
     pub hold_mino: Option<Mino>,
     pub score: i64,
+    pub game_speed: f32,
 }
 
 impl GameData {
@@ -94,6 +95,7 @@ impl GameData {
             show_ghost,
             hold_mino: None,
             score: 0,
+            game_speed: 0.5,
         }
     }
 }
diff --git a/src/main.rs b/src/main.rs
index 347ce08..3bf70aa 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -147,7 +147,12 @@ fn main() {
             if *exit_flag_rc.lock().unwrap() {
                 break;
             }
-            thread::sleep(Duration::from_secs_f32(0.5));
+            let mut game_speed = 0.5f32;
+            {
+                let rustris_rc = rustris_rc.lock().unwrap();
+                game_speed = rustris_rc.game_data.game_speed;
+            }
+            thread::sleep(Duration::from_secs_f32(game_speed));
             {
                 let mut rustris_rc = rustris_rc.lock().unwrap();
                 if !rustris_rc.move_mino(1, 0) {
@@ -169,8 +174,9 @@ fn main() {
                 }
             }
             {
+                let mut rustris_rc = rustris_rc.lock().unwrap();
                 let mut stdout = stdout_rc.lock().unwrap();
-                let buf = rustris_rc.lock().unwrap().show();
+                let buf = rustris_rc.show();
                 execute!(stdout, Print(buf)).unwrap()
             }
         }
diff --git a/src/rustris.rs b/src/rustris.rs
index 6041ecd..8373850 100644
--- a/src/rustris.rs
+++ b/src/rustris.rs
@@ -43,6 +43,7 @@ impl Rustris {
         }
 
         self.game_data.score += clear_lines * 100;
+        self.game_data.game_speed += 0.01 * clear_lines as f32;
     }
 
     pub fn get_next_mino(&mut self) -> Mino {