HERE, or buy it on Steam. I'm sure most of you at least know what steam is. Most people refer to it as either a minecraft copy or a 2-D minecraft. While some aspects of that are true, I wouldn't even call it a copy. Anyway, what you do is create a character and world. The character customization is decent. For the world you name it and select either Small, Medium, or Large. And then you start of with basic tools. (Pickaxe for digging and potentially hurting. Axe for Chopping wood and potentially hurting. and a Sword for only hurting. I feel like I'm forgetting one I can't remember.) And you have to make shelter. During daytime the only real enemy you'll be facing is slimes.
There are 4 special different area's in the world. Theres the Corrupt which takes medium skill to go into with decent gear. The hallow which in my opinion is harder than the corrupt. The Jungle which is harder than corrupt but not as hard as hallow. And the underworld which is the easiest in my opinion. There are two stages to the game, Normal then Hard basically. You start out in normal and after you defeat a boss in the underworld called the "wall of flesh" your world changes to hard. And boy do things get harder. Mobs get harder, there are new bosses to fight which are extremely hard. etc.
I have about 70 hours of gameplay in this game on steam. It's a good game and worth the $10 I think it is. I recommend trying it out.