Minecraft is a sort of a combination between an adventure and a building game. The name is self-explanatory, you will have to do a lot of mining to get resources, with which a very wide variety of items can be crafted. It features a lot of game modes, however I found that the survival and creative ones are the most interesting. These modes are supported in single and multiplayer game styles.
To begin playing you first have to create a world. Here is where you'll be able to choose the game mode and select a difficulty. The difficulty matters when you're playing in the survival mode, not in the creative mode. A thing that bothered me was that, there isn't really a tutorial within the game to explain all of its features. However, the game is intuitive and in no time you'll get the hang of it.
The survival mode combines elements of adventure, creativity and exploration. Basically your main goal in this mode is to survive as long as possible. You start with nothing and you are left free to roam and to do absolutely whatever you want as long as you survive. The difficult thing is that at night, monsters will appear that will try to kill you. You can choose to fight the monsters by crafting your own weapons and armor, or you can avoid them by creating an impenetrable house. Another thing in this mode is that some monsters also appear in shadows, or caves. And usually, the very good resources are found in the deepest caves. So the game also has a bit of suspense, because you have to be prepared at all times, which really makes the game even more interesting.
The creative mode is for creating your own world. You can create anything you want, as big as you want, meaning that you have total freedom. It definitely brings a sense of satisfaction to creating your own world because it isn't like anybody else's, and you can also show it off in the multiplayer.
The gameplay mechanics are probably some of the best out of any other game. You gather resources by hitting the blocks until they break. With those you can craft items. Basic items can be crafted by arranging them in a certain way in your inventory's craft section. More complicated ones require a crafting table, which you have to create first. Items can vary from cosmetic ones to armors, weapons, tools that will help you gather resources faster and torches which will allow you to see in the dark.
The only thing that may throw off new players, is the graphics quality. The game indeed looks very out-dated and brings back memories from the ones in the 90s. However once you play it, and realize how much fun it can be to have so much freedom in a game, it will most likely change your mind. Whole castles can be built, with draw-bridges and complicated mechanisms, and you can do this along-side friends in the multiplayer. Finally I can say that it is a great and wonderful game. It has created so much buzz in the last few years that now it has almost 7 million people playing.