The game is incredibly cheap, immensely fun, lasts for ages, has tonnes of replayability, an abundance of content, supports multiplayer beautifully, and covers almost no space whatsoever. It does not push your PC to its limits performance-wise, thus most devices I'd assume would run it without issue. The modding community is both plentiful, and the game allows modding for even those who have no experience with it whatsoever. So, even if you are done with the Vanilla game, you can add in a lot of new content without having to pay for any DLC.

Terraria is a game that I've been on and off with for ages and I cannot ever drop it. Whenever I want to challenge myself with bosses or want chill out by building or mining, Terraria is a perfect choice. It has been semi-ironically called a Minecraft clone since it was first popularised, but (no hate for MC) the game offers much more in the way of creative content. The two games are prominently similar in their use of cubes (or squares in this case (?)) and the fact that they are both sandbox games. However, the primary mechanics of each game are quite different, I would say that Terraria offers a more complete experience.

There are so many different elements and dimensions in the game. Even the most bland sounding game mechanic, like fishing, is made to be actually rewarding and useful. It offers a plethora of decorative options for those who are less interested in min-maxing and challenging themselves. But even for someone who is looking to push themselves, the game offers you a multitude of combat options, the ability to manipulate terrain opens up the ability to strategise against bosses in creative ways. You can familiarise yourself with a selection of classes all of which offer different paths to combat. The accessories you can make/find, the potions you can brew, and the ammunition you can obtain all give you an advantage, and these items are not always "better" than each other. The combination of certain accessories may boost a certain class specifically, or they may provide you with overall benefits, depending on how you want to play the game.

The bosses and the events within the game are all unique, in the sense that you cannot adopt the same strategy and fighting style for every boss and streamline the process (unless you are an expert at the game I guess), and thus it makes the game more compelling.

Deserving of the Labour of Love Award

TL;DR:
I could write more and explain it even further, but the simple fact is: The game is exceptionally cheap compared to the experience it offers. Worth every single penny (or whatever currency you use)