The tech tree

Every part in the game is sold by one node on the tech tree, and discovery is what buys nodes. This is where a career turns from one rocket into a fleet.

What it is

The tree is a grid of nodes, joined by lines that say which one comes before which. Buying a node puts its parts in your hangar palette for good. Nothing else does: a part you have never seen in the palette is a part whose node you have not bought yet.

You reach it from the Space Center. Tap Center in the hangar, tap the Research Centre, and its sheet has Open tech tree on it. The tree is far wider than a phone, so you drag it with a finger and pinch to zoom; Fit in the header pulls back to the whole thing at once, and Close returns to the Space Center.

The tech tree showing tier 1 and the edge of tier 2. Rocketry and Staging are ringed green and read open; Aerodynamics and Solid Boosters are ringed amber with their price in discovery; the tier 2 nodes behind them are dim and read tier 2. — Three states, all on one screen. Green and "open" is bought. Amber with a price is buyable now. Dim, reading only its tier, is out of reach.

What a node costs

Almost every node is priced in discovery, the currency that buys nothing else. Aerodynamics, the cheapest, is 12 discovery; Interplanetary Comms, the dearest, is 78 discovery. Two nodes are priced in credits instead. Nothing on the tree is ever priced in both, and the whole tree comes to 1,480 discovery plus 70,000 credits if you buy every one of the 34 nodes.

One node, Rocketry, is free and you already hold it the day you start. It sells the Command Pod, the Fuel Tank, the Engine, the Fin and the Parachute, which is exactly the rocket the game opens with, and it is what makes Earth a place you can launch from.

Where discovery comes from is a subject of its own: see Credits and discovery. In short, feats and readings pay it and nothing else does.

Tiers, and the Research Centre

The tree is banded into three tiers, drawn as vertical stripes with TIER 1, TIER 2 and TIER 3 written over them. Your Research Centre's level decides how many of those bands are open: level 1 opens tier 1, level 2 opens tier 2, level 3 opens tier 3. A band you have not opened says TIER 2 · LOCKED across the top and every node inside it is dim, whatever else you have bought.

Tapping a node in a locked band does not waste your time. Its card's button turns into the Research Centre's next extension, priced and bought right there, so the tree never sends you to another screen to open the band you are looking at. The level prices are in the Buildings reference.

What a node needs first

Most nodes name one or two other nodes you must already own. The card lists them under Requires, each with a tick or a cross, so a node you cannot buy tells you the whole way to it in one glance. The lines on the grid are the same information drawn: a line lights up green once the node it leads to is yours.

Two nodes ask for something else as well: a feat you have already done. The Lunar Pad waits until you have landed on the Moon, and the Mars Pad until you have landed on Mars. Their cards list that alongside the nodes, marked "(achievement)", and the line under the card names what is still missing.

The Lunar Pad node selected. Its card reads Launch pad on Moon, Tier 2, and a Requires list with a tick beside Landing Gear and a cross beside One Small Step (achievement). The Unlock button is greyed and priced at 20,000 credits, with the line Needs the One Small Step achievement first below it. — The cross beside One Small Step is the whole reason this button is grey. The price, 20,000 credits, is not the problem here.

Two nodes open a new world

Most nodes sell parts. Two sell a place to launch from instead: the Lunar Pad at 20,000 credits and the Mars Pad at 50,000 credits. Buying one founds a Launch Pad on that world, puts the world on the Space Center's tabs, and makes it a choice in the hangar's destination picker.

Landing on the Moon does not give you a pad there. It lets you buy the node that does. That is the order every time: fly there the hard way first, then pay to make it a place you start from.

What buying one changes

The tile turns green and reads "open", the lines out of it light up, and the parts appear in the palette on the spot. The card then says "These parts are in your palette." A node that opened a world says "Its pad stands at the space center." instead. There is nothing to fit, install or launch first; the node is bought once and it is yours for the rest of the game.

Note

Nothing on the tree can be bought in sandbox. The tree you see there is the one your account really holds, and the card says so: "Sandbox: the tree stays as the shared world has it." Switch back to the shared world in Settings to spend anything.