1] It's a sandbox game.
You basically have an open world. 8 times larger than the surface of the Earth. With a semi realistic environment. Every world is unique and randomly generated by the game. And since it's a sandbox game there's really no limits on what you can do. There's no such thing as a set of objectives that you need to do in a finite amount of time. You're free to destroy or create.
2] It's Educational.
Most educational games that I've ever encountered are not as quite addictive as Minecraft. I know what you're thinking, Minecraft wasn't designed to be an educational game. Minecraft promotes creativity, teamwork, critical thinking skills, statistics and plethora of other things. Think of it this way, would you prefer letting your kid play with toy guns and kill imaginary monsters or let them play Lego for hours? In Minecraft, a kid or an adult can play creatively with their friends and even have the joy of blowing up stuff. Minecraft has already made its way to classrooms in the US via Minecraft EDU.
3] It's just freaking endless. (Mods and Texture Packs)
Got bored? There's almost an infinite amount of modifications you can do with the game from adventure maps, HD textures, more things to craft, more animals, magic, industrialization, nuclear power, more biomes, more weather, more dimensions and the list just goes on and on. There's nothing impossible as long as somebody has the will.
4] The following is huge.
It doesn't matter how old you are. You'll fit just right in here with the whole community. The Minecraft fanbase is as passionate as Doctor Who or Starcraft fans by comparison and it's truly amazing. Youtube is full of Minecraft videos since the alpha era to the present version of the game. It's a hit.
5] And it's not finished.
Mojang still gives updates. Bug fixes, optimizations, and even more stuff to play with. It always feels new even for veterans. Upon the time of writing this post, there have been over 10 milion copies of the game sold and around 17,000 copies from the last 24 hours alone.
And these are 5 things why Minecraft is awesome. If you have enjoyed reading this post please share! I'll be posting more stuff like this in the BattleVortex site so stay tune.