Hold the Line

How to play

1. You command the Colonial Guard's last outpost in a desert canyon. The Myriad, an insect swarm, pours out of a glowing rift in the west and claws toward your colony's gate in the east. Every creature that reaches the gate costs the colony some integrity, and at zero the colony falls. Hold it through thirty waves.
2. Pick a structure from the bar below the canyon (or press 1 through 7), then click or tap a tile to build it. The swarm walks around whatever you build, so your walls and guns are the maze; you can narrow the canyon, but never seal it. The chevrons on the ground show the route the swarm will take.
3. Barricades are cheap walls; upgraded, they grow razor wire that slows anything brushing past, then a shock fence. Sentry Guns shoot anything, on the ground or in the air. Incinerators burn the ground swarm, armor and all. Mortars shell crowds from long range but can't hit what's next to them. Rail Lances charge, then fire a slug through everything in a line. Flak Batteries hit only fliers. Sensor Arrays reveal burrowers and, upgraded, make everything they see take extra damage.
4. Skitters are fast and many. Spitters jam a nearby structure with acid for a few seconds. Husks are armored: gunfire barely scratches them, while fire, blasts, and rail slugs cut right through. Gliders fly straight over your maze. Delvers burrow, and nothing but the orbital strike can hit them unless a sensor sees them. Hatchers burst into skitters. Every tenth wave brings a behemoth, whose stomp silences the structures around it.
5. Click a structure to see what it does, upgrade it (U), change what it shoots first (T), or sell it (X). A structure built during a break refunds in full until the next wave starts; after that, or if you built it mid-wave, it refunds three quarters. Without a mouse, pick a structure with 1 through 7, move the cursor with the arrow keys, and press Enter to build; [ and ] step through the structures you have.
6. Wave 1 starts when you send it (N, Space, or the Send button). After every wave you get a short break, and sending the next one early pays a bonus for each second you skip. Kills and every wave you hold pay credits.
7. When the orbital strike is charged, press O (or its button) and pick a spot: a beam from orbit hits it a moment later. It recharges slowly, so save it for a behemoth or a breach.
8. Drag (or right-drag) to pan, scroll or pinch to zoom, press Q and E to turn the view, and R to reset it. F changes the game speed. P or Esc pauses, and M mutes. Daily plays today's canyon, and Seed plays a canyon by its code, so friends can race the same one. Gfx changes the graphics quality.

Your best score is kept on this device. The canyon is drawn in 3D with Three.js.