On release terraria was critisized by the huge amount of Minecraft fans as "just a 2D Minecraft". Is it true? In a way, yes and in a way, no. How come?
As I first started the game, all alone in the wilderness, I started exploring the retro-looking surrounding my little Gnyrll character had been thrown into. Ok... there's trees... and dirt... and stone... let me just-- wait wrong controls... Ok now I got my wooden box palace of comfort and safeness surrounding me. Oh what survival skills minecraft has taught me I thought. Well, then came night and the zombies came. Sounds familiar? Yep, it sure is minecrafty alright.
But oh it was dark... And where could I find torches? Coal! "Nope." Said my terraria playing friend on skype, of course it had to be the slimes that appear on daylight and in deep dungeons. Apparently the gel they drop is both tasty (potions) and flammable. I wonder why slimes won't explode when I shoot my flaming arrows at them. Hmm... Maybe that would cause some creeper-like problems to your creations. SSSSSSSHHHH
|Eye see you|
|Om Nom Nom|
Popping some defence in your "town" is useful also against certain events that sometimes happen either when night falls (blood moon) or the sun rises (goblin invasion). These events make enemies more stronger and grant them the magical ability to - oh shit - open doors! This would certainly be welcome in minecraft too... Atleast the creepers would enjoy it.
I won't cover up all the things to do in Terraria, cause this text would be even longer than it is right now. Theres so much to do from exploring underground jungles, crafting epic gear or climbing up to floating islands and so much more. I hope you have seen how this game is a lot different than Minecraft though the basics are the same. I'd say that if you like a more monster slaughtering or a rpg - like experience than minecraft, Terraria is for you to explore.
So Invite your friends and take the time to spend that 10$ on something more than beer! :)