Minecraft is a game where you can build your own world in a given space and tools. The main aim of the game is construction. The cubical blocks are of different materials like sand, dirt, water, etc and can be arranged as we like.
Minecraft Launcher is a free application that can be downloaded from the developer website. On running, it will automatically update the game files with the latest version. You will be able to play the game without an Internet connection if you've run the launcher at least once while connected to the Internet.
The launcher is free but you have to pay for the game.