Minecart Track

You do not need to own a cart to ride one. Stand near a line and hit the quick mount key, or activate a spot on the rail directly, and a cart appears with you already sitting in it. What happens on the second option is a hidden hook dragging you over, which is why it fails under a low ceiling: with less than four tiles of headroom you get pulled to the rail and left standing there. Leaving is the mount key again, a hook, or cancelling the buff, and the cart vanishes when you do. Jump off, land on solid ground and try to walk, and it also disappears. Almost everything works while riding, weapons and tools included. Hooks are the exception.

Left and right speed you up, slow you down, or turn you around, and with nothing held the cart keeps whatever speed it has until something stops it. Reaching top speed takes a few seconds and the cap is firm, although a well timed jump nudges you slightly past it. You fall through platforms while riding, which matters the first time a line crosses your house.

Rails cannot be walked on, so building a long line on foot means building a floor for yourself as well. The answer is to lay it while riding. Set a slow cruise, hold the placement button, and the cart builds its own road out in front of itself while you do nothing. Around 11 mph is the sweet spot. At 12 the cart overtakes your placement and comes to a stop a few dozen blocks in. Accessories that speed up block placement push the ceiling to roughly 18 mph. This is the cheapest way to build a skybridge, and unlike a solid one it will not block meteors from landing. Smart cursor extends an existing line horizontally or diagonally for you.

Hammer the final tile to cycle three endings. The closed one looks like a wooden fence and brings you to a harmless stop. The open one looks like more track and throws you off the end, with ordinary fall damage waiting unless you land on more rail. The bumper looks like a metal fence and sends you back the way you came, which is what you want at both ends of a commuter line. Anything the world generated ends closed, and so does anything you place, until you decide otherwise.

Where three rails meet you choose your branch by holding up or down as you pass through. Hammering the middle tile changes which branch you take when you hold nothing, and wiring the junction turns it into a switch you can throw from a lever or a pressure plate track, which is how a whole network gets driven from one room. Reading them is the fiddly part. When you place two lines next to each other one connection is always left open, and on a horizontal join the tell is whether there is wood underneath the rail. The states always advance in the same order, so going back to one you just passed means two more swings. Four rails crossing at right angles gives you a true crossing with no switching at all, and the elaborate five and six way arrangements have dozens of hammer states before they loop, which is more novelty than transport.

With the slot empty you get the wooden cart, which is noticeably slower than everything else. Most alternatives are cosmetic and differ only in the trail they leave behind. The ones that are not: the Minecart Upgrade Kit is Expert only and gives every cart a large speed jump plus lasers that shoot at things for you. The Minecarp keeps full speed through water without letting you breathe in it. The Demonic Hellcart grants a few seconds of lava immunity that stacks on top of a Lava Charm. The Digging Molecart is slower than the wooden one but tunnels and lays its own rail as it goes, provided you carry both the track and a strong enough pickaxe, and it only works horizontally and below the surface. Carts take dye from the slot beside them, including the plain wooden one.

Running something down at speed hurts it, and it hurts more the faster you are moving, with a floor below which nothing happens at all. Kill it at full speed and none of the damage comes back at you. More usefully, a cart outruns every pre Hardmode boss and most Hardmode ones, so a long straight line is a genuine arena: you are faster than the thing chasing you and both hands are free the entire time. The classic use is a skybridge run against wyverns, which you can simply outpace while collecting Souls of Flight. Teleporters affect everything in the space above them, riders included, so a line can be spliced straight into a teleport network. Running on Asphalt Block beats an ordinary cart on raw speed, but asphalt costs more to lay and asks you to keep holding a direction, while a cart at cruise asks nothing at all.