Mining, dungeon crawling, and spelunking. This is the main resource acquisition element of the game. It essentially consists of digging or exploring underground, hoping for the random appearance of valuable blocks which can be used in the construction of more advanced tools, machines, and buildings. Natural cave systems may sprawl for miles underground, twisting and snaking their way through the earth from the surface to the bedrock. "Dungeons" may also appear, as a simple room with a monster-spawner in the center, or may manifest as (extremely rare) "Strongholds" that are much more complex. Other features, such as abandoned mineshafts and large ravines may also appear.
Construction. This is the part of the game that has the most in common with Classic, previously described in the main entry. You take the stone and other materials you get from mining, and build houses, towers, or any other structure that takes your fancy. Given that Minecraft's environment is cube based, this forces a bit of creativity for players looking to build something other than "giant cube #258". However, due to the large number of different blocks, and the fact that players can dye wool blocks a variety of colorful hues, players can get very creative indeed.
Engineering. Minecraft has a substance called "redstone". Redstone dust, when placed by the player, can carry "power," which is kind of like a direct current of electricity. The redstone system is essentially an emulation of Real Life non-integrated electronic circuits, which you can use to control the behavior of certain blocks and items in the world. For example, a player can build a locked door that only opens for about a second when a nearby button is pushed, or wire an on/off switch to a floodgate that allows them to turn a waterfall on and off like a light, or rig a pressure-sensitive plate connected to a machine that fires a volley of arrows at whatever stepped on the plate.
Exploration. Minecraft's world, and its various landscape and "biomes", are procedurally generated as the player ventures into unexplored areas. Thus, the map is, for all practical purposes, infinite (though it's often said that, due to technical limitations, the engine would crap out at around 8 times the surface area of Earth). Additionally, players are eventually able to craft their own Portal Network of Cool Gates, (apparently inspired by the Wheel of Time series) which allow players to travel throughout the world at eight times the normal rate, if you don't mind the risks. Of course, some people build portals just to explore the "Nether", which contains several unique resources like netherrack, a strange mineral that can burn forever, or glowstone, which is a useful light source and potion ingredient. A safer traveling alternative would be using boats or minecarts.
Farming. There are a number of different types of plants and animals that can be farmed for resources. Trees can be grown for wood, a common and versatile building material, and wood can be turned into charcoal, which is used to cook food, smelt ore, and craft torches. Sugar cane can be grown for sugar or paper. Cacti can be grown for defensive purposes and dye production. Wheat, mushrooms, watermelons, apples, cocoa beans, potatoes, and carrots can be grown for food. Pumpkins can be grown to make Jack-O-Lanterns, golems, and special helmets that provide protection against Endermen. Nether wart, which has rather different growing conditions, is an important potion ingredient. Chickens lay a few eggs every day, and can be killed for meat and feathers. Cows can provide milk, as well as meat and leather if you have a sustainable breeding population and enough wheat to feed them. Sheep produce wool, which can be dyed sixteen different colors and used for decoration, or made into a bed to change your spawn point and make nighttime pass faster.
Combat. The game contains a number of different AI-controlled monsters which will attack you on sight, forcing you to run or fight. Once defeated, they drop various valuable resources, as well as experience orbs which the player can collect and eventually spend on enchantments for their equipment. Generally the AI ranges between stupid to mildly competent, and direct unmodded combat is rather limited, consisting of either using a sword or a bow; however, critical hits and over-charged bow shots are possible, and there are plans to expand combat further. The difficulty can be adjusted to make monsters more or less powerful. The "peaceful" setting removes monsters altogether. Conversely, the "hardcore" setting, intended as an arcade-like highscore challenge, locks your world onto the hardest difficulty and doesn't let you respawn, so you have to start a new world if you die.
Looting. While you can harvest raw materials and food, they can only get you so far. To get the better items to help you survive or to make the more advanced tools, you'll need to kill the hostile mobs like Creepers and Skeletons to get the better materials. There are also randomly generated structures like villages, dungeons, abandoned mines and strongholds that have chests with valuable and rare items, such as diamonds, obsidian, iron weapons/tools, iron ingots, and much more. Villages are found randomly on the surface while dungeons, mines, and strongholds are usually found deep underground.