Build a maze of towers across floating sky islands and hold the line.
Bastion Line is a tower defence game set on islands drifting high above a sea of clouds. Creatures of the Murk pour out of rift gates and march toward your Heartstone; every one that reaches it costs you lives. You stop them by building towers on the turf, and because towers block the ground, every tower you place also bends the road the enemy has to walk.
That makes it a maze-building game as much as a shooting gallery. Enemies always take the shortest open route, a glowing arrow trail shows you exactly where that is, and the game never lets you seal it completely, so the puzzle is to stretch the path as long as possible through the range of your towers. Six towers with three visible upgrade tiers each, eight kinds of enemy, fifteen hand-built isles, an Endless mode and a seeded Daily Siege give you plenty to master, while the sky turns from morning gold to dusk to moonlit night as the waves roll in.
How to play
- Pick a tower from the build bar at the bottom of the screen (or press 1 to 6) and click an empty turf tile to build it. On a phone, tap a tile once to preview the tower and its new route, then tap again to build.
- Enemies walk from the rift gates to the Heartstone along the shortest open path. Towers block tiles, so use them to build walls and corridors that force a longer route. The arrows on the ground show the current path; while you hover a tile they show the route your new tower would create, and a red cross means that tile would seal the path completely.
- Each wave starts on its own after a short build phase, or press Send (Space) to call it early for bonus gold. The card at the top right previews the next wave so you can prepare for flyers, stealth or shields.
- Click a tower to upgrade it (U), sell it (S) or change who it shoots at: the first enemy in line, the last, the strongest or the closest (T). Each upgrade visibly rebuilds the tower taller, with more parts and a brighter crystal.
- Clear every wave to win the isle. Lose all your lives and the line falls. Fast-forward (F) plays the action at two or three times speed.
Controls
| Action | Keyboard | Touch | Gamepad |
|---|---|---|---|
| Choose a tower | 1–6 or click the build bar | Tap the build bar | LB / RB, or A on an empty tile for the radial menu |
| Build | Click a tile (Enter on the cursor tile) | Tap a tile to preview, tap again to build | Left stick moves the cursor, A builds |
| Upgrade / sell / targeting | Click a tower, then U / S / T | Tap a tower and use its panel | A on a tower opens its radial menu |
| Send next wave | Space | Send button | X |
| Fast-forward 1× / 2× / 3× | F | Speed button | Y |
| Camera | Mouse wheel zoom, right-drag orbit, drag to pan, Q / E rotate | Drag to pan, pinch to zoom, twist with two fingers to rotate | Right stick orbit, LT / RT zoom |
| Cancel / deselect | Right-click or X | Tap the selected tower again | B |
| Pause / restart | Esc / R | Pause button | Start / Back |
Every action can be remapped in Settings.
Modes
- Campaign
- Fifteen floating isles. Build a maze, hold the line, clear every wave.
- Endless
- Pick an isle and survive wave after wave for as long as you can.
- Daily Siege Daily
- Today's seeded isle and wave modifiers, the same for everyone.
Tips & strategy
- Build walls, not islands. A single tower in the open barely changes the route; a line of towers anchored to the edge of the isle or a boulder forces enemies to walk all the way around it.
- Leave the long corridors you create inside the range of as many towers as possible. A Mortar or Storm Coil in the middle of a zig-zag hits the same enemies several times as they pass.
- Frost Spires multiply everything else: slowed enemies spend longer in range of every tower around them.
- Wyverns fly over your maze along the isle's natural route, so keep Ballistas, Storm Coils or Arcane Obelisks near it. Mortars and Flame Braziers can't hit them.
- Shades are invisible until an Arcane Obelisk sees them (or a splash hits them). If the wave preview shows a Shade, build an Obelisk on its route first.
- Storm Coils deal double damage to Warden shields; Mortars and Arcane bolts crack Golem armour that shrugs off Ballista bolts.
- Sell refunds everything during the same build phase, so experiment freely before you send the wave.
- Call waves early when your defence is ahead: the bonus gold adds up, and it keeps the boss waves from catching you underbuilt.
Achievements
- Holding the LineClear any isleLocked
- UntouchedClear an isle without losing a single lifeLocked
- Master BuilderUpgrade a tower to its third tierLocked
- LabyrinthStretch a path to three times its original lengthLocked
- Giant SlayerDefeat a TitanLocked
- Storm CallerHit six enemies with one lightning chainLocked
- Dragon's HoardHold 2,000 gold at onceLocked
- UnbrokenSurvive 25 waves in EndlessLocked
- Skyforge KeeperClear the fifteenth isle, Skyforge CitadelLocked
A short history of the genre
Tower defence grew out of custom maps for real-time strategy games around the turn of the millennium, where players stopped building armies and started building turrets along a road. The best of those maps let you place towers anywhere, so the defence itself became the maze.
Standalone browser and mobile games then made the genre a staple: tower upgrade paths, targeting priorities, fast-forward buttons and wave previews all became standard tools. Bastion Line keeps those conventions and the pure maze-building of the early maps, with a fair rule that you can never fully block the path, and sets it on floating islands with a day-to-night sky.
FAQ
Is Bastion Line free?
Yes. It runs in your browser with no download or sign-up. The site is supported by unobtrusive ads that never cover the game.
Can I block the enemies completely?
No. The game checks every placement and refuses any tower that would cut a rift off from the Heartstone or trap an enemy already on the board. A red cross marks those tiles.
Does it work on phones?
Yes. Tap the build bar to pick a tower, tap a tile to preview it and tap again to build. Drag to pan, pinch to zoom and twist with two fingers to rotate the camera. It plays in portrait and landscape.
What is the Daily Siege?
A seeded isle with two wave modifiers (such as faster enemies or pricier towers) that is the same for every player on the same day. Your best score of the day is saved and you can share it.
How do stars work in the Campaign?
Clear an isle without losing a life for three stars, losing no more than 30% of your lives for two, and any clear for one. Clearing an isle unlocks the next one.
Does it support controllers?
Yes. The left stick moves a cursor over the board, A opens a radial build or tower menu, X sends the next wave, Y fast-forwards and the right stick moves the camera.
Where are my scores saved?
In your browser on this device, along with your campaign stars. You can export your profile from the Profile page and import it on another device.
Updates
- Bastion Line launched with 15 isles, Endless mode and the Daily Siege.
