Belts is a factory-building tower defense that you play in your browser, for free, with nothing to install and no account. You and an opponent, the AI or another player online, get the same map, the same start and the same waves. You build a factory that feeds your core, hold the routes into it with turrets that fire what the factory makes, and send enemies at each other. The first core to run out of lives loses.
Every plate your factory makes can go one of three ways, and there's never enough for all of them:
Bank it. Belt it into your core, where it pays for buildings, research and sends.
Fire it. Turrets draw their ammo from the core, so every shot comes out of the same stock you build and send with.
Upgrade it. Feed it to assemblers: iron plates into gears, and gears and copper into circuits, which the best of everything costs.
You start with 100 lives, 80 iron and 40 copper in your core, and a small factory: one line of iron and one of copper, belted into it. The first wave comes after 45 seconds, and after that there are 20 seconds to build between waves. You can build while a wave is on too, and start the next one early when you're ready.
Hover your stock in the top bar to see where it all goes: what comes in, what your turrets fire, and what you spend.
Your factory
Iron and copper ore lie in fields around your base. A drill on ore mines it, a smelter turns ore into plates, and belts carry the plates into your core. Assemblers make plates into things worth more:
Iron plates, from smelting iron ore.
Copper plates, from smelting copper ore.
Gears: two iron plates each, in a gear assembler.
Circuits: a gear and two copper plates, in a circuit assembler.
Machines push what they make out of their arrow side, onto a belt or straight into the next machine.
Belts carry items forward into whatever they point at. A belt can feed into the side of another.
Underground belts carry items under anything, the enemy lane and the river included, up to 5 tiles.
Nothing can be built on the river, and belts can't cross it except underground.
Removing anything gives back all it cost.
Logistics
Belt 1
1 iron
Moves items forward. Drag out a line and release to build it; drag back over it to undo, right-click or Esc to cancel.
Inserter 2
4 iron, 4 copper
Picks items up from behind and drops them in front (~1.1/s). Takes from belts and machine outputs; only picks what the target can use.
Splitter 3
4 iron, 4 copper
Deals items in turn to its front, left and right. Use it to divide a line. With nothing picked to build, click one of its sides to shut or open it.
Underground 4
8 iron, 4 copper
Carries items under anything, even the enemy lane. Place an entrance, then an exit up to 5 tiles ahead facing the same way. Priced per end.
Production
Drill 5
16 iron, 8 copper
Place on ore. Mines 0.8 ore/s and pushes it out the arrow side.
Smelter 6
12 iron, 12 copper
Turns any ore into its plate (2/s, enough for ~2 drills).
Gear asm. 7
18 iron, 18 copper
2 iron plates → 1 gear (1/s). Gears are armour-piercing gun ammo, and most mid-game buildings need them.
1 gear + 2 copper plates → 1 circuit (0.5/s). Circuits feed late research, tesla coils, railguns and the big sends.
Adv. drill 9
16 gears, 6 circuits · Research: Advanced drills
Place on ore, or click straight over an old drill. Mines 1.7 ore/s.
Defense
Enemies come at your core three ways: on foot down the lane, by ship up the river, and through the air along the dashed line from where the lane comes in. All three end at your core, so what you build around it covers all three; further out, each needs a defense of its own.
Turrets draw their ammo from your core, wherever they stand. A belt or an inserter feeding one directly keeps it topped up instead, and spares the core.
Guns fire iron plates, or gears (G, or the gun button in the top bar). Gears do three times the damage and pierce armour, but they're also what you build, research and send with.
Turrets aim at the enemy closest to your core, except the railgun, which picks the one with the most HP.
Turrets
Gun turret Z
10 iron, 16 copper · Ammo: iron plates or gears · Hits everything
Rapid fire at one target. Ammo: iron plates, or gears (triple damage, ignores armour); G picks which it draws from the core.
Mortar X
30 iron, 16 copper, 8 gears · Ammo: iron plates · Hits enemies on foot and ships · Research: Ballistics
Lobs shells a long way that burst over a whole group, on land or water. Ammo: iron plates. Can't hit aircraft, or anything right next to it.
Goes on the shore, next to water. Fires torpedoes that ignore armour, at ships only. Ammo: gears.
Ships and planes of your own
Two bigger buildings field units of their own. Each sortie's ammo comes out of your core while the unit rearms, and nothing the enemy has can hurt them.
A 2×2 dock on the shore. Launches two patrol boats that sail out to fight ships on the river (and shoot anything else in reach), then come back to rearm. Each sortie costs 4 iron and a gear.
A 5×2 airstrip (R turns the runway). Its two strike fighters take off whenever enemies are about: they chase down aircraft first, otherwise strafe and bomb whatever is closest to your core, then land to rearm (6 iron and 2 gears a sortie).
Carrier
Research: Carrier group
Every shipyard also launches an aircraft carrier with two fighters of its own. It holds station partway up the river: a floating runway.
Upgrades
Click one of your turrets, with nothing picked to build, for its upgrades. Every kind has two paths of two steps. The first step you buy picks the turret's path and closes the other one for good; the second can follow whenever you can pay for it. Upgrades cost gears, and most of them circuits too, and removing the turret gives all of it back.
Copy (Q, or the button on a turret's card) picks a turret as your tool, upgrades and all: click open ground to build another like it, or drag over turrets of the same kind to bring them up to it.
Gun turret
Rapid fire
Autoloader11 gearsFires 50% faster.
Twin barrels25 gears, 4 circuitsFires two and a half times as fast as a plain gun.
Marksman
Long barrel11 gears30% more range, 35% more damage.
Sniper25 gears, 4 circuits60% more range, more than double damage, and every shot ignores armour.
Mortar
Heavy shells
Big bore25 gears50% more damage over a wider burst.
Cluster shells53 gears, 11 circuitsMore than double damage, and half as wide a burst again.
Field gun
Quick loader25 gearsFires 60% faster.
Howitzer53 gears, 11 circuitsFires well over twice as fast, 25% further, and right up to its own feet.
Tesla coil
Arc
Forked lightning28 gears, 11 circuitsArcs through 8 enemies, jumping further.
Storm coil53 gears, 28 circuitsArcs through 12 enemies, harder.
Overcharge
Capacitors28 gears, 11 circuits60% more damage.
Overload53 gears, 28 circuitsTwo and a half times the damage, a little faster.
Cryo tower
Deep freeze
Coolant21 gears, 5 circuitsSlows by 60%.
Absolute zero42 gears, 18 circuitsSlows by 72%, for half as long again.
Wide field
Wide nozzles21 gears, 5 circuits30% more reach.
Blizzard42 gears, 18 circuits60% more reach, and the frost bites: six times the damage.
Railgun
Capacitor bank
Fast charge53 gears, 25 circuitsFires 50% faster.
Rapid rail88 gears, 63 circuitsFires well over twice as fast.
Heavy slug
Tungsten slug53 gears, 25 circuits50% more damage along a wider line.
Siege rail88 gears, 63 circuitsWell over double damage, nearly twice as wide.
Flak cannon
Airburst
Big shells21 gearsWider bursts, 25% more damage.
Proximity fuses46 gears, 9 circuitsBursts nearly twice as wide, 70% more damage.
Quad mount
Four barrels21 gearsFires 50% faster.
Radar46 gears, 9 circuitsFires well over twice as fast, 25% further.
Torpedo tube
Heavy warheads
Big warhead25 gears50% more damage, a wider blast.
Ship killer49 gears, 11 circuitsWell over double damage, nearly twice the blast.
Twin tubes
Second tube25 gearsFires 60% faster.
Salvo49 gears, 11 circuitsFires well over twice as fast, 20% further.
Enemies and waves
A round is a build phase, then a wave down every route into your core. Both players get the same waves. The first 12 are set, so that each new enemy turns up on its own, with a warning the round before; after that, each wave's theme is drawn for the match: Horde, Blitz, Armoured column, Warband, Swarm, Air raid, Naval assault, Combined arms and Mixed. The wave in the top bar shows what's next, and hovering it shows the two after.
Bosses come every 5th wave from wave 10, taking turns: Titan, Hive Queen and Carrier. A boss that reaches your core takes every life you have left; anything else costs a few.
Modifiers. From wave 11 every wave gets one, and from wave 20 two: Armoured (+2 armour), Swift (+20% speed), Regenerating (heal 2% HP/s) and Tough (+30% HP).
Bounties. Clearing a wave pays iron and copper, and gears from wave 6: 50% more if nothing got through.
Each wave brings more enemies than the last, each of them tougher, so a defense that's falling behind lets part of a wave through rather than all of it at once.
Grunt
From wave 1 · On foot · Costs 2 lives if it gets through
Plain infantry.
Runner
From wave 3 · On foot · Costs 2 lives if it gets through
Fast and fragile.
Gunboat
From wave 4 · On the river · Armour 1 · Costs 2 lives if it gets through
Sails up the river to your core. Anything that can reach the water can hit it.
Brute
From wave 5 · On foot · Armour 3 · Costs 4 lives if it gets through
Armoured: iron plates do half damage. Gears, mortars, tesla coils and railguns cut through.
Medic
From wave 6 · On foot · Armour 1 · Costs 2 lives if it gets through
Patches up the enemies around it. Kill it first.
Mite
From wave 7 · On foot · Costs 1 life if it gets through
Comes in swarms. Mortars and tesla coils shred them.
Drone
From wave 8 · In the air · Costs 2 lives if it gets through
Flies straight at your core, ignoring the lane (the dashed line). Mortars can't hit it.
Broodmother
From wave 9 · On foot · Armour 1 · Costs 5 lives if it gets through
Bursts into 6 mites when it dies.
Titan
Boss, from wave 10 · On foot · Armour 8
Boss: if it reaches your core, you lose. Armour 8: only gears, tesla, mortars and railguns really hurt it.
Destroyer
From wave 11 · On the river · Armour 4 · Costs 6 lives if it gets through
A heavily armoured warship. Torpedoes, mortars and gears cut through.
Bomber
From wave 12 · In the air · Armour 2 · Costs 6 lives if it gets through
A heavy, armoured plane on the drones' line. Flak, fighters and tesla coils bring it down.
Hive Queen
Boss, from wave 15 · On foot · Armour 4
Boss: if she reaches your core, you lose. Lays mites as she walks and bursts into two broodmothers.
Carrier
Boss, from wave 20 · On the river · Armour 5
Boss: if it reaches your core, you lose. An aircraft carrier: launches jets at your core as it sails up the river.
Jet
Comes with the Carrier · In the air · Costs 3 lives if it gets through
Launched by carriers, straight at your core. Fast.
Sending
The buttons on the right of the bottom bar send packs of enemies at your opponent. Every send raises your income for good: it's paid into your core every 6 seconds, the same however late it was sent. The cheap packs pay best for what they cost, and from the Brutes on they pay gears and circuits too, so you can live on sending rather than on a big factory.
Late sends hit harder. Packs grow 15% a round, but their price only 6%.
The more you send, the dearer it gets. Every enemy you send puts a little on the price of all your sends from then on, by how big it is: after 1,000 points' worth (a grunt counts 1, a Titan 40), sends cost twice their list price.
One pack at a time. Sends leave one after another, and the packs waiting to leave are your send queue, which holds 6. Your opponent sees your queue as Incoming, and you see theirs.
A boss can end it. A Titan or a Carrier that isn't stopped takes every life the other core has.
6 Grunts
From round 1 · 18 iron, 12 copper · +11 iron a minute
Down their lane.
6 Runners
From round 2 · 10 iron, 22 copper · +6 iron, +6 copper a minute
Down their lane.
2 Brutes
From round 4 · 10 iron, 12 gears · +6 iron, +4 copper, +2 gears a minute
From round 8 · 40 iron, 28 gears, 6 circuits · +8 iron, +8 gears, +2 circuits a minute · Research: Carrier group
Up their river.
Titan
From round 8 · 36 gears, 20 circuits · +10 iron, +10 copper, +14 gears, +5 circuits a minute
Down their lane. A boss: if it gets through, their core falls.
Carrier
From round 12 · 70 gears, 45 circuits · +15 iron, +15 copper, +24 gears, +9 circuits a minute · Research: Carrier group
Up their river. A boss: if it gets through, their core falls.
Research
Research (T, or the button in the top bar) is the fourth place your production can go: one project at a time, paid for up front and done after its research time. Cancel one and you get it all back. There are four branches, each a ladder where every step needs the one above it, with a few links across. What a project unlocks turns up in the build bar or among the sends when it's done.
Industry
Deep drilling Drills mine 30% faster.
40 iron, 30 copper · 20 s
Express belts Belts, undergrounds and inserters move items 60% faster.
50 iron, 30 copper · 20 s · Needs Deep drilling
Electronics Unlocks the circuit assembler.
50 iron, 60 copper, 12 gears · 30 s · Needs Deep drilling
Assembly lines Smelters and assemblers work 50% faster.
The map is bigger than the board you start on: there's a strip to the east and one to the south, in shade until they're claimed. From wave 4, click one to see what it would bring and what it would let in. Each player claims them for themselves. The first costs 150 iron and 110 copper; the second 260 iron, 190 copper and 40 gears.
Room to build, and rich ore: drills on a frontier's ore fields mine 50% faster.
An outpost that takes in whatever you belt into it, like your core, so there's no running belts all the way home.
Bigger bounties: every wave you clear pays 40% more for each frontier you hold.
Its lane opens, and joins yours. From the next wave, 45% more of every wave comes down it, 25% tougher than the rest, and sends can come that way too.
Ways to play
Against the AI
Play on the main menu starts a game against the AI, at the level picked under it:
Easy. Takes it easy, for learning the game: it keeps less defense than it needs, sends a third as much and never a boss, and never upgrades.
Normal. A real opponent: it reads your defense and keeps its own ahead of what's coming, and sends a boss if yours couldn't stop one.
Hard. Plays to win, by the same rules as you: it mines every ore field it can reach, claims both frontiers, reads your defense and sends what it can't stop.
Hax. Hard, and it cheats: everything that reaches its core counts double, and its research takes a third of the time.
The AI plays a real base on its own copy of the map, by your rules (only Hax cheats). It goes by what you could see too: your base, your research and the packs in your send queue, but not what's in your core. How much it leans on sending is different each game, and you're told at the end.
Online
Play online looks for another player. While you wait it shows a link: send it to a friend and they're put straight into a match with you. Whoever comes first, a stranger or the friend, is your opponent. There are no accounts, names or rankings.
There's no pause and no fast-forward, and starting the wave early is a vote: it comes once you've both pressed Ready.
Leaving the match, or closing the page, gives your opponent the win. If your connection drops, you have 20 seconds to get back in.
Sandbox
Sandbox is a match with nobody else in it, for trying things out: everything is researched, nothing costs anything, and no wave comes until you start it, whichever one you pick. Sends come down your own routes.
Maps
Every game is on a random map, the same for both players: a new winding lane, a new river and new ore fields. New map on the main menu rolls another.
Watching your opponent
The mini view in the corner shows your opponent's base, live. Click it, or press Tab, to look round it: their turrets and upgrades, their research, their planes and boats, and what they're saving for.
Coming back to it
A game against the AI, or the sandbox, is saved in your browser as you play. Close the page, open it again, and you're back where you were, unless a new version of the game has come out in between.
Controls
Mouse and keyboard
Click build · drag for beltsRight-click remove, for a full refundR rotate · Q copy · Esc cancelWheel zoom · drag or WASD to pan · 0 fitN start the wave · Space pause · F speedTab your opponent's base · G gun ammoClick a turret to upgrade itClick a splitter's side to shut itT research · H help · L muteEsc the menu: sound, music, quit1234 belt, inserter, splitter and underground56789 drill, smelter, gear asm., circuit asm. and adv. drillZXCVB gun turret, mortar, tesla coil, cryo tower and railgunEYPO flak cannon, torpedo tube, shipyard and airfieldShift and 1 to =: the 12 sends, in order
Touch
Tap a tool, then the map, to buildDrag with the belt picked: lay a lineDrag move the map · Pinch zoomThe cross in the build bar: removeThe arrow in the build bar: turn what you're placingTap a turret: its upgrades, and CopyTap anything for what it isThe speaker in the top bar: sound, music, the menu
Questions
Is Belts free?
Yes. It runs in your browser, with nothing to download and no account to make.
Can I play on a phone or a tablet?
Yes, by touch, either way up. Add it to your home screen and it opens full screen, like an app.
Can I play with a friend?
Yes: press Play online and send your friend the link it shows. You'll both get the same map and the same waves.
How do I win?
Run your opponent's core out of lives. Every enemy that gets through costs a core a few, and a boss costs it all of them, so a Titan or a Carrier that your opponent can't stop wins the game.
What happens if I close the page?
A game against the AI is kept in your browser: open Belts again to carry on, as long as the game hasn't been updated since. An online match is lost if you leave it, though if your connection drops you have 20 seconds to come back.