The Game view is invoked by pressing the Play button, and acts as a realistic test of your game. It also has settings for the screen ratio, which will come in handy when testing how much of the player's view will be restricted in certain ratios, such as 4:3 (as opposed to wide) screen resolutions. Having pressed Play, it is crucial that you bear in mind the following advice:
In Play Mode, the adjustments you make to any parts of your game scene are merely temporary. It is meant as a testing mode only, and when you press Play again to stop the game, all changes made to active game objects during Play Mode will be undone. This can often trip up new users, so don't forget about it! Unity can help with colors. You can set a color overlay for the Unity interface itself for the Play Mode. In this way, when you are in Play Mode, the Unity interface will be colored with that color. Go into Edit | Preferences | Colors to change it to something other than full white (no color change).
This also works in the black Unity Plus Unity Pro interface. Another cool thing you can do while in Play Mode is copy a whole GameObject, a group of game objects, or a component of a GameObject while in play and paste it after you stop the execution. This is very handy while editing your game.
The Game view can also be set to Maximize when you invoke Play Mode, giving you a better view of the game at fullscreen, in other words, the window expands to fill the interface. It is worth noting that you can expand any part of the interface in this way, simply by hovering over the part you wish to expand and pressing the Spacebar.
In addition to using Play to preview your game, the live game mode can also be paused by pressing the Pause button at the top of the interface, and play can be advanced a frame at a time using the third Advance </span>Frame button next to Pause. This is useful when debugging, which is the process of finding and solving problems or bugs within your game development.