Available now · iPhone & iPad
Modstack
Build small programs. Make big moves.
Stack command tiles to guide a robot. No typing — just big readable tiles that combine into surprisingly short programs.
Inside Modstack
Build it. Run it. Refine it.
Real screens from Modstack 1.0, from the opening circuit to layered command stacks, live circuitry, and the complete visual guide.
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 tiles placed, not moves made. Any solution works; beating par unlocks the next circuit.
Live circuitry
Later chapters add ordered relays, switches, and gates. Their boards change mid-run as your program powers the circuit piece by piece.
36 handcrafted circuits
Six chapters cover Foundations, Compression, Routing, Mastery, Circuitry, and Expert Circuits. Each introduces one idea at a time, then combines 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.
Fair pricing
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. A one-time $3.99 Full Game Unlock opens 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.
Download Modstack free on iPhone or iPad. Build small programs, make big moves, and solve the Foundations chapter plus an Easy Daily Circuit before deciding whether to unlock the complete game.
Modstack — Resources