Games have their own user interface styles. Much of the fun in a game is related to the design of the user interface. Game Designers spend a remarkable amount of tie on user interfaces. It's often more difficult and time consuming than the design of the actual game. The same is true in Ready. That's because Ready is built on a professional-grade game engine called Unity. Game engines are amazing products: They provide game designers with physics engines to simulate the real world. Ready exposes a "2D physics engine".
Game engines typically favor quick results around physical mechanics. For example, in Ready, saying physics on, gravity on, material bouncy, add behavior stay in frame with reaction reflect takes a few taps for an experienced maker. Then on play, a remarkably complex series of equations are solved, which makes the object bounce around the screen, nearly never in exactly the same way! Having to write equations from scratch ti generate this realistically, and then provide all the options to tune the mechanic, could easily take...a year! It took Unity many years of development, with many programmers working to arrive at their current physics engines. Thanks to their effort, the game engine handles modelling the world for you, leaving you free to do the creative work around the game mechanic, tuning the game play, and designing game art to put in the game.
User interface doesn't come out of the box in quite the same way as physics. Successful user interface design is a creative art, and requires, as with architecting a building, a lot of patience. It's best done step by step, rather than all at once. Testing the user interface is also essential (along with the overall game play), to make sure people understand at every moment where they are, and what they can do next.
Objects in Ready can be placed on one of three layers.
Scene: Objects you can interact with.
Background: Objects behind the scene objects. They can't be affected, but can't collide with objects in the scene.
User interface: a layer in front of the scene, like a glass wall, where buttons can go. These also cannot collide with objects in the scene. They also don't move when the camera moves from one scene to another.