Thumb & Pylon

About this app

Thumb & Pylon is a tower defense game for phones where you are the power supply. You tap a glowing core to make charge, and every tower you build drinks that charge to fire. Build too much and the whole line goes dark mid-wave. Build too little and enemies walk past. Every wave comes down to what you can afford to stop doing.

It’s made for tower defense regulars and idle-game fans who want a fresh mechanic with no pay-to-win. There are 34 hand-built levels in four acts, each introducing one new idea, plus nine towers that each play differently, daemons you can hire to tap for you, ten hazard enemies, bosses and a preview of every wave before it lands. World leaderboards cover every level. The game plays fully offline, with no ads, no purchases and no sign-up.

How we built it

The problem

Tower defense and idle clickers are two popular mobile genres that rarely meet. We wanted to make tapping the fuel rather than the whole point, so every tap spent powering a tower is a tap not spent on anything else. That tension only works if the numbers are right, and a leaderboard only means something if the scores on it are real.

What we shipped

The game runs natively on iPhone, iPad and Android from one TypeScript codebase built with Expo and React Native. The board is a tilted 3D neon grid drawn with three.js, and the interface uses React Native Skia. Players can drag, pinch and rotate the board, play at up to three times speed, and pause to inspect every upcoming wave. The look changed during testing: around the first playtest the game moved from a 2D tile map to the neon grid, and the ghost preview for placing towers came straight from tester feedback.

Under the hood

The core decision was to keep the game rules in their own engine, separate from rendering, so a level plays out exactly the same way on every device. That made two things possible. World leaderboards are checked by our own server instead of taking a submitted score on trust. And balancing became measurable: scripted bots play every level with fixed strategies, and their results set the star thresholds. When a bot kept losing, the cause was usually a mispriced level rather than one that was too hard.

The trailer was cut from real gameplay footage with Remotion.