Neon Swarm: From Concept Art to a Playable Game

Five weeks after the first post, the tower defence game has a name, eighteen levels in three worlds and a soundtrack written in code, and it plays from start to finish. Here's where it stands.

It has a name

In the first post I didn't have a name for it. Now it's called Neon Swarm - Tower Defence. On your home screen it's just Neon Swarm, because the full name gets cut off under the icon. Inside the project, everything is still called TowerDefence, and I'm leaving it that way.

The home screen, running in the iOS Simulator. Still no sun.

Where it stands

Every level is playable from start to finish. Here's how the plan from the first post has gone:

The plan, so far

Skeleton & shell✓ Done: the screens, saved progress and settings

Maps & roads✓ Done: every invader walks the roads with its own rules

Towers✓ Done: six towers, three tiers each

The lookMostly done: a couple of touches from the concept art still to land

Game loop✓ Done: waves, credits, lives, building, upgrading and speed

Content✓ Done: 18 levels in three worlds, all balanced

PolishWell under way: real devices and TestFlight to go

Three worlds

The campaign is three worlds of six levels each. You earn up to three stars on a level for the lives you keep, and stars open up the next world.

Level select open on the Neon City tab, showing level cards for Warp Gates, Split Lanes and Relay with map thumbnails, stars and best results — Level select, open at Neon City.

Sunset Strip is where it starts: a violet and pink sky, wireframe mountains, palm trees and pyramids. It teaches the basics, like roads that merge, roads that cross, and flyers that ignore the road altogether.

Night Drive on Sunset Strip: a laser beam hits invaders on the road while other towers wait by the road to the core — 1-4 Night Drive on Sunset Strip. A laser takes on the invaders rounding the bend.

Neon City opens at 6★: a lit skyline, a cyan grid, tower blocks and billboards. It brings in warp gates, where invaders vanish and surface somewhere else, along with forks in the road and armoured convoys.

Warp Gates in Neon City: a lit skyline above a cyan grid, with all six tower types firing at a swarm of invaders near a warp gate — 2-1 Warp Gates in Neon City, with all six towers in play.

Chrome Coast opens at 18★: the sea and a lighthouse on the horizon, an aqua grid, beach umbrellas and surfboards. Its roads have turbo lanes that speed invaders up and sand drifts that slow them down, and it introduces the Patcher, which repairs the invaders around it.

Its levels are named after the things that keep developers up at night: Boot Sequence, Overclock, Patch Tuesday, Memory Leak, Fork Bomb and Kernel Panic.

Patch Tuesday on Chrome Coast: the sea and a lighthouse on the horizon, an aqua grid, and towers firing at invaders on a stretch of sand drift, with a turbo lane of pink chevrons near the core — 3-3 Patch Tuesday on Chrome Coast. The pink chevrons are a turbo lane, and the sandy stretch at the top is a sand drift.

Six towers, nine invaders

There are six towers (the Blaster, Rocket Pod, Laser, Tesla Coil, Cryo and Mortar), each with three tiers. Tap a tile and a radial menu shows what you can build, with a preview of its range. Tap a tower to upgrade it, change what it aims at (first, last, strongest or closest), or sell it for 70% back.

Damage comes in two kinds, kinetic and energy, and invaders defend against them differently: armour blunts bullets, shields soak up energy, and only some towers can hit anything that flies. A good defence is a mix, not a wall of the same tower.

The nine invaders are the Glitch, Runner, Tank, Swarm, Shielder, Splitter, Flyer, Overlord and Patcher. Each has one rule to learn, such as armour, a shield that grows back, splitting into fragments, flying over the road, dropping swarms, or repairing the convoy around it.

Learning as you go

The first level doubles as a six-lesson tutorial: the goal, building, power nodes, starting a wave, upgrading and calling the next wave early. After that, the game introduces things as they turn up. The first time a new invader or tower appears, a card explains it, and the Field Guide has a page for every one of them. A preview under the wave button shows what's coming next.

The first tutorial lesson on First Light: a panel explains that invaders come through the gate and follow the road to the core, and that each one that gets through costs lives — The first of six lessons on the very first level, First Light.

It sounds like something now

The first post was all about how it looks, and the sound ended up following the same rule: nothing pre-made. There are no audio files in the game. All 21 sound effects and four songs are synthesised in code, and the grid pulses in time with the music. There are haptics too, for building, leaks and the end of a level.

Built to stay smooth

The 120 fps target from the first post still stands. On top of that, the game now keeps an eye on the device. When it's running hot, in Low Power Mode or on battery saver, it lowers its frame rate and trims the glow and particles to match, rather than cooking your phone.

Keeping it honest

There are 105 automated tests. Because the rules live apart from the graphics, most of them run on the Mac without a phone or even a simulator. The ones I lean on most play through every level on their own, so if a change makes a level too easy or too hard, I find out straight away instead of three worlds later.

What's next

Real devices. So far it has all run in the Simulator, which tells you nothing about real performance. The frame rate target needs proving on actual iPhones and iPads.
TestFlight. Getting it into other people's hands.
The last touches. A couple of details from the concept art still need to make it into the game.

Going from concept art to something you can play start to finish was the big step. Next is making sure it holds up on a real phone.