My first thought of this was "ugh, more minecraft copys", but oh boy was I wrong. Minecraft is nothing compared to this gem.

The world of Terraria is an amazing one, a ton of itens, NPC's, enemy mobs and most of the bosses are hard af on the first few times.
You can play it in various ways (like "giving" your char a class), find ridiculous weapons (looking at you rainbow shooter) and mounts.
There are special events that happen troughout the time you play (Slime Fall, Eclipses, Blood Moons...).
2 modes, Normal (for new players and less skilled ones) and Expert (more punishing but also more rewarding for veteran players).
Building is pretty simple here but that doesn't mean you can't create beautifull bases. (But then again we always make those square ass rooms for NPC's)
Easy to host and play with your friends.
Easly one of my all time favourites games and very cheap also. (around 2-3€ at sales)