Guide:Ideas

So, you've mastered your world but ran out of things to do. There are still many options for playing with your current world, or making the next game far more challenging.

Projects
You probably already built some of the building projects, try upgrading them. However, if you didn't build one in the current world you are playing in, try them now! Feel free to browse the Terraria forums for ideas and inspiration.
 * Hellevators for rapid travel upwards and downwards.
 * Skybridges and railways for similar travel across the map.
 * Mushroom & Plant Farms.
 * Battle Arenas.
 * Traps and other structures for farming monsters.
 * Shooting Range: Connect one or more Bird Statues (or even other statues including enemies) to a Timer or a Switch. Then use a gun to shoot at the spawned creatures. Make it more challenging by adding a few obstacles in the arena and close off the arena to prevent the prey from escaping.
 * Multi-boss fight: If you have defeated every boss in Terraria, try summoning and fighting multiple bosses at once.
 * Make complex devices with Mechanisms, Wiring, and Hoiks.
 * Kill the Dungeon Guardian.
 * Try to collect one of every fish in the game.
 * Try to get all of the achievements.
 * Make a teleported system for another form of easy transformation.

Art
Terraria's sandbox offers vast opportunities for creativity. Reshape your map and create varied structures: You can range from elegant simplicity to intricate complexity, realistic to fantastic, and from the beautiful to the terrifying or hideous.
 * NPC Houses: Some simple decorations can quickly turn any house into one that fits the theme of a NPC. For example add some Plants and a Flower Wall to the house of your Dryad, some Bottles and a Bed for your Nurse, a Crystal Ball for your Wizard, an Ammo Box for your Arms Dealer, or some Christmas decoration for Santa Claus. All NPCs have some items that suit their theme, allowing you to build some nice houses for all.
 * Castle: One of the most popular constructions in Terraria is a castle. Of course you can build a simple symmetric castle, but this tends to look rather boring. A good way to build a more interesting castles is by building some tower tops of varying sized and varying heights, and then connecting them. For colors the Gray Bricks and Red Bricks combine well, while some more expensive bricks may look good for the throne room. Use your own imagination to build the way you like it.
 * Mine: Not only is it handy to have direct access to a large mine but it looks great too. Using some Wooden Beams, Planked Walls and torches you can make a simple and good-looking mines for yourself.
 * Tree House: You can either build your own tree house or edit a Living Tree. Make sure to use some more natural blocks and walls to make it look better.
 * Outposts: You can build outposts in the different biomes, usually in the style of the biome it is build in. This allows you to easily buy items that NPCs only sell in specific biomes.
 * Themed Houses: There are many furniture themes in Terraria. For example take a look at the different Doors that are available. You can make a house (or other structure) for each of those themes.
 * Pyramid: Make a giant above ground pyramid, half maze and half trapped to make a worthy burial chamber.
 * Domes: Build large glass domes with a biome inside of every dome.
 * Treasure Chamber: You may not have noticed yet, but you can place Coins, Bars and Gems. This can be used to make a great looking treasure chamber.
 * Atlantis: You can build cities basically everywhere. Below the ground, in the skies, but also underwater. This is one of the difficult constructions to build, as you tend to drown, you move slow underwater and it's dark. Furthermore, you properly want to drain the water out of your constructed building, while still allowing you to easily enter this. Luckily there are solutions to all those problems. For building underwater you properly want to use Gills Potion or a Neptune's Shell, allowing you to breath permanently underwater. To provide you with light you can use a Light Pet. To drain the water you only need a single Lava Bucket. To allow entrance, without buildings being flooded make an entrance from below using Platforms.
 * Sky Tower: Build a tower reaching all the way into space.
 * Museum: There are many items to display in Terraria. For example you can make rooms to display Statues, Paintings, Trophies, Armors, Banners, Butterflies, Critters, and Weapons.
 * Pixel Art: Using different colored blocks, you can make sprites inside your world. Try making your own character too! Gemspark Blocks will work better, especially if you want your creation to be visible in the dark.

For The Next Game
You've defeated all the bosses, got the best equipment and built a fantastic base. But what to do next? There are many options to make future games more challenging.

Game Settings
The game itself offers several settings which can make things far more challenging:
 * Expert mode is an option for world creation. Enemies and bosses become tougher, with more health, new attacks and debuffs and AI improvements. Enemies now collect dropped coins and despawn with them, while you respawn significantly slower. On the flip side, enemy loot increases sharply, and bosses drop Treasure Bags with powerful and vanity items that are only available in Expert mode.
 * Difficulty is an option for character creation. The character's difficulty mode applies no matter what world they enter. There are three options here:
 * Softcore mode is the default; softcore characters only drop half of their coins when they die.
 * Mediumcore mode makes on death to drop their entire inventory at the point of death, including equipment, accessories, and ammo.
 * Hardcore mode: when a Hardcore character dies, they drop all carried items, and also become a Ghost. In this state, they can fly and pass through walls, but not affect the world in any way. In Multiplayer, ghosts are invisible to other players, but can still use the "chat" system to talk with them. When they exit the world, the character is permanently deleted; while items in the world (including items dropped at death, stored in chests etc.) are unaffected, any items in "personal storage" are lost forever.

Player versus Player

 * Join a PvP server, or host one yourself, and compete against other experienced players.
 * You can play games such as Capture the Gem, or straight up PvP battles. A good and exotic arena can make PvP more interesting.

Personal Challenges
Sometimes the game is too easy and you want to add an additional challenge, setting extra rules for yourself. This isn't enforced by the game, but only by your own determination. Some examples are listed here.
 * Only use ranged, melee, or magic weapons weapons. You can use your starter sword until you acquire your weapons of choice if needed.
 * Don't use any Potions.
 * Don't use any NPCs.
 * Don't use any storage items.
 * Beat the game without crafting items.
 * Beat the game with only crafted items.
 * Never increase your health past 100.
 * Play as the Merfolk, by permanently equipping a Neptune's Shell and Fish Bowl and being unable to breathe air. (Origin)
 * Play as dark elves by never setting foot above ground. (Origin)
 * Reversed Gravity: Use an inventory editor to obtain a Gravity Globe or 100 Gravitation Potions to permanently reverse the gravity. (Origin)
 * Buckethead: Equip a Bucket at the start of the game and never unequip it. (Origin)
 * Bomberman: Mine by only using Explosives.
 * Use no Armor. (Origin)
 * Fairy: Cleanse the Corruption and spread the Hallow. Settle and live only in the Hallow.

Adventure Maps
You can play maps made by other players, or create your own adventure map and share it.

Mods
There are various Mods available that introduce new items and enemies to Terraria, or alter the game rules. It is generally a good idea to backup your world and characters before installing any mod, as trying to remove a mod afterwards can "break" your world or character files.