An orthographic camera is commonly used when designing 2D games within Unity and setting up an orthographic camera is pretty simple:
Step 1 : Set position to x=0, y=0 and z = -10 (any depth that you choose depending on the Z values of your game objects).
Step 2 : Rotation to x=0, y=0 and z=0
Step 3 : Scale to x=1, y=1 and z=1
Step 4 : Change the ‘Projection’ drop-down to Orthographic (default is Perspective).
Step 5 : Set Camera size to 5 (this number can vary – with my game resolution a size of 5 worked).
Step 6 : Create some objects (I added three simple cubes) and change Ambient Light to light grey via Edit > Render Settings > Inspector > Ambient Light (colour chooser). You can use any light colour or if you prefer stick to the default black ambient light and add some lights to the scene.