You can many, MANY THINGS. The gameplay takes a few months minimum, and after that you can do several things that are fun. You can make golf courses for minigames, or a marble run. You can fish which isn't exactly exciting, but it is sometimes really good. You can make simple mini games with weapons and friends (provided you even obtained either of those). Examples include "tank wars" which literally is just putting your character somewhere on uneven terrain, and using a projectile weapon, parkour which is also great with hooks and wall climbing gear for good mobility, and many others I ain't gonna list because of how many there are. Even if this isn't interesting you can practice building on servers, or just get several tiles to see what you can build. There is so much more "depth" in terraria's building because of the amount of detail. Now if you are so incredibly unhappy with this continuously expanding list of fun and interesting things you could partake in... you could join minigame servers so you can play games with mechanics, or code your own. I haven't even mentioned mods yet, and this is already enough for several years of exploration. Mods are incredibly easy to access, granted you bought the game from steam, which is where most people will get the game. The mods like Calamity, Thorium, and others make playing the game a whole different experience. For instance the new Calamity update added such a cool boss, with really difficult and complex attack patterns that make you feel powerful when you beat it. mods, golf, fishing, building, or minigames not enough? Make a nice looking character, or try different playstyles.