Honestly, this is the best game of the 2D genre in my opinion. Are you able to make an orchestra with a huge amount of musical tools in any other game?
1. A ridiculous amount of planets to explore.
2. Musical tools. They are absolutely amusing. And there is so much of them!
3. The crafting system is amazing, so much different stuff to craft. And as you craft something, you get to craft even more! In addition to a huge crafting system, you can find blueprints in chests and learn some new craftings!
4. The planets aren't as big as I would like them to be, but they are still huge. You run around planets and you find buildings, ruins and stuff like that. It is so interesting to explore them!
5. There are side quests. You find a village on one of the planets and the NPCs can give you quests, and they reward you with a bag with random stuff! In addition to that, you have a chance to recruit them!
6. Different types of items. By that I mean common, uncommon, rare and legendary. Not sure if there is something between rare and legendary, but it makes the game so much fun for grinding.
7. Fishing. You have a chance to catch each fish, from common to legendary. You can craft only two fishing poles, and that's a bit lame, but they might add it in the future. You have some upgrades to the fishing poles, but you can't craft them, only catch them from uncommon fish and higher. With a chance of course. Which again, pretty lame, but at least they have a fishing system that looks absolutely sweet!
8. Vehicles. There is like, 4 "cars" and one boat, that you can purchase with pixels, but they look very cool.
And more stuff that I probably forgot to mention.
1. The main quest is the worst thing in the game. You need to explore planets and scan random stuff to get points, and after like 50 points you complete the quest. You return - get a quest to beat a boss - you beat the boss - you get the same quest but for another race. Pretty lame I have to say.
2. Not hardcore. Why do I say "not hardcore"? Because I've completed like two main-story bosses and went grinding for the best equipment (second to best), got some legendary weapons, and then completed all of the following bosses without having a challenge at all. Even the last boss wasn't that hard. I did not die to any boss, except one time that I fell into a trap and died. Basically, what am I trying to say is that the main story bosses got no effect on your gameplay. It's just, text that you read, go defeat a boss, finish the quest. The design of the bosses and the mechanics are pretty cool though. It's a bit hard to explain, but they are like... Simple mobs that you have to kill from a side quest, but they have more hp and the reward is better. In Terraria we had a lot more challenge defeating the bosses, even with two players.
Overall, the game is amazing. If you exclude the main quests, and look at the game without it, you can see a game that is better than Terraria by its degisn. 9/10.