This a simple flappy bird game designed using native html , css and javascript
Create a canavas for your desired width and height
Draw the canvas with your desired color
Draw a rectangle on the canvas at your desired location to treat as a bird
Set Y-velocity and gravity to the box
Calculate the Y-position of the bird using simple phy(velocity=distance/time)
Add Jump speed to the box
Replace the box using a bird image and backgorund using your desired background
Add top and bottom pipes and set them with velocity
Now detect the collision and stop the game if collide
Calculate the score and write reset function
Enjoy the game