Cat Stack - Offline One-Tap Puzzle Game

Overview

Cat Stack is an offline, one-tap block-dropping puzzle for children (target age ~5, one finger, no reading required after the first level). A crate slides across the top of the screen — tap once and it drops into that column. The cat walks itself forward and climbs the staircase you build, until it reaches the golden fish.

The One Rule

The cat can step up one crate or down one crate. Nothing else. That single rule makes the game instantly readable for young players while still leaving room for genuine planning as the levels open up.

Key Features

One-tap controls — tap to drop a crate; the cat handles the climbing
Endless, always-solvable levels — terrain is generated, solved exactly, then accepted or rejected, so no level can ever soft-lock
Four worlds — Daytime, Sunset, Night and Jungle share one layout but swap the palette
Star ratings — finishing under par earns up to 3 stars; stars never gate progress
No pressure — no lives, no timers, no punishment loop; running out of crates is a gentle “stuck” pose with a tap-to-reset
Fully offline — progress, stars, speed and sound settings persist on the device, and the game never needs a network

Art Direction

A deliberately mixed look: the scenery is flat vector art (one sky colour per world, a ringed flat sun, layered mountains, grass over dirt), the crates are smooth framed faces tiled edge-to-edge, and the cat and fish are 8-bit pixel sprites on a 4px grid. Menus and buttons reuse the crate face, so the whole UI feels carved from the same material.

Audio

One continuous looping track plus drop, land, step, win and stuck effects, synthesised from scratch in Python and dedicated to CC0 — bundled with the app, nothing streamed at runtime.

Tech Stack

Flutter with the Flame engine for the gameplay scene
Provider for app state and repositories
A level generator with an exact minimum-crate solver (par) and unit tests
Google Mobile Ads (child-directed) and in-app purchase for an optional one-time “Remove ads”, both isolated and optional
Bundled Lilita One and Nunito fonts, fully offline