Awaiting App Store review · Turn-based programming puzzle
Modstack
Build small programs. Make big moves.
Stack command tiles to build tiny programs that make a robot perform surprisingly large moves. No typed code — just large, readable tiles, clever modifiers, and circuits that feel inevitable in hindsight.
The puzzle language
A tiny vocabulary. One powerful rule.
Every program is built from Move, Turn Left, and Turn Right. Modifiers stack on top: Mirror flips a turn, Repeat doubles the action. The board is the world; the program track is the plan.
Move forward one board cell in the robot’s current direction.
Turn Left and Turn Right rotate the robot 90 degrees in place.
A modifier that swaps Left and Right. Two Mirrors cancel out.
A modifier that executes the resolved instruction twice. Stack two for ×4.
36 handcrafted circuits · 6 chapters
Precise, tactile, clever.
The stack is the star
Every program slot holds a stack up to three tiles deep: one base command, plus modifiers that transform it. Move + Repeat + Repeat marches the robot forward four cells from one slot.
Small programs, large outcomes
Par counts the physical tiles you place — not the actions they produce. Any working route is acknowledged, but compressing it under par is what powers the next circuit open.
Live circuitry
Later chapters add ordered relays, switches, and gates — boards whose state changes mid-run as your program powers the circuit piece by piece.
36 handcrafted circuits
Six chapters — Foundations, Compression, Routing, Mastery, Circuitry, and Expert Circuits — each introducing one idea at a time, then combining them deliberately.
Daily Circuit
One deterministic puzzle per difficulty each calendar day — Easy, Medium, and Hard. Compact, replayable challenges in the same puzzle language as the campaign.
Premium restraint
The first chapter is free, and a single one-time purchase unlocks the rest. No ads, no subscription, no account, no currencies, no streak pressure. Progress stays on your device.
A fair one-time unlock
Play the first chapter free.
The full Foundations chapter and the Easy Daily Circuit are free. One single purchase unlocks the remaining 30 circuits and the Medium and Hard Daily Circuits.
No ads. No subscription. No account. No currencies or consumable hints. Locked content is shown honestly — an unexpected paywall never interrupts active play.
Stack commands.
Solve circuits.
Modstack is complete and awaiting App Store review. Leave your details and we’ll let you know the moment it’s available.
Modstack — Resources