Gameplay is the specific way in which players interact with a game
When you start a new world, you are met with a user interface which allows you to customize your world. You are able to customize the world name and seed, along with the sea level, rainfall, temperature, continent size, mountain height, hills size and hills height. Some variables affect others, e.g. higher temperature results in higher sea level. You are also able to select mods to use in this world.
How long days, years and seasons last is controlled by the time variable. The game constant can be changed when playing on servers, otherwise the player can dynamically change between 'Pause', 'Normal' and 'Fast' speeds using the buttons in the top left corner while playing single-player. One day is equivalent to 1/8 of a year, and seasons change every two days. Most flora replenishes after 3 days.
You are able to dig to sea level in any location, but there is a limit to how steep slopes can be made. In order to dig deeper, you will need to have adjacent tiles steeper.
As you dig down, the material changes in order: