diff --git a/include/states/game-state.hpp b/include/states/game-state.hpp
index b711e97..4f86966 100644
--- a/include/states/game-state.hpp
+++ b/include/states/game-state.hpp
@@ -4,6 +4,7 @@
 #include <SFML/Graphics.hpp>
 #include <iostream>
 #include <sstream>
+#include <cmath>
 #include "engine/include/state/state.hpp"
 #include "engine/include/game/game.hpp"
 #include "states/pause-state.hpp"
@@ -17,6 +18,16 @@ class GameState : public pte::State
     sf::Sprite background;
     sf::Sprite pause_button;
 
+    // demo things
+    float pi = 3.14159f;
+    float ballRadius = 10.f;
+    float ballSpeed = 400.f;
+    float ballAngle = 0.f;
+    sf::CircleShape ball;
+
+    void init_ball();
+    void update_ball(float delta_time);
+
 public:
     GameState(pte::game_data_ref data);
 
diff --git a/src/states/game-state.cpp b/src/states/game-state.cpp
index 4a1a14a..c38b689 100644
--- a/src/states/game-state.cpp
+++ b/src/states/game-state.cpp
@@ -9,6 +9,8 @@ void GameState::init()
     this->data->assets.load_texture("Pause Button", PAUSE_BUTTON);
     pause_button.setTexture(this->data->assets.get_texture("Pause Button"));
     pause_button.setPosition(this->data->window.getSize().x - pause_button.getLocalBounds().width - 10, pause_button.getPosition().y + 10);
+
+    init_ball();
 }
 
 void GameState::handle_input()
@@ -32,11 +34,57 @@ void GameState::handle_input()
 
 void GameState::update(float delta_time)
 {
+    update_ball(delta_time);
 }
 
 void GameState::draw(float delta_time)
 {
     this->data->window.clear(sf::Color(56, 42, 55));
+    this->data->window.draw(this->ball);
     this->data->window.draw(this->pause_button);
     this->data->window.display();
 }
+
+void GameState::init_ball()
+{
+    ball.setRadius(ballRadius - 3);
+    ball.setOutlineThickness(3);
+    ball.setOutlineColor(sf::Color::White);
+    ball.setFillColor(sf::Color::White);
+    ball.setOrigin(ballRadius / 2, ballRadius / 2);
+    ball.setPosition(SCREEN_WIDTH / 2, SCREEN_HEIGHT / 2);
+
+    do
+    {
+        ballAngle = (std::rand() % 360) * 2 * pi / 360;
+    } while (std::abs(std::cos(ballAngle)) < 0.7f);
+}
+
+void GameState::update_ball(float delta_time)
+{
+    // move ball
+    float factor = ballSpeed * delta_time;
+    ball.move(std::cos(ballAngle) * factor, std::sin(ballAngle) * factor);
+
+    // check colisions
+    if (ball.getPosition().x - ballRadius < 0.f)
+    {
+        ballAngle = -ballAngle + pi;
+        ball.setPosition(ballRadius + 0.1f, ball.getPosition().y);
+    }
+    if (ball.getPosition().x + ballRadius > SCREEN_WIDTH)
+    {
+        ballAngle = -ballAngle + pi;
+        ball.setPosition(SCREEN_WIDTH - ballRadius - 0.1f, ball.getPosition().y);
+    }
+    if (ball.getPosition().y - ballRadius < 0.f)
+    {
+        ballAngle = -ballAngle;
+        ball.setPosition(ball.getPosition().x, ballRadius + 0.1f);
+    }
+    if (ball.getPosition().y + ballRadius > SCREEN_HEIGHT)
+    {
+        ballAngle = -ballAngle;
+        ball.setPosition(ball.getPosition().x, SCREEN_HEIGHT - ballRadius - 0.1f);
+    }
+}
\ No newline at end of file