Modus Ponens
Rate itLight each room by proving it: a daily puzzle of pure propositional logic.
Every day: One new logic puzzle every day, the same for everyone: a map of rooms, each a proposition, to light by proving it. New puzzle: Midnight, your local time.
Modus Ponens is a minimalist daily puzzle game built on intuitionistic propositional logic. Each level is a map of rooms, every room a proposition, and you light a closed room by touching the rooms that prove it. Solving a puzzle quietly proves a formula, which is kept as a trophy.
About Modus Ponens
Modus Ponens turns logical proof into a quiet puzzle of light and rooms. Each level is a map in which every room stands for a proposition, and the shapes of the rooms' outlines stand for the connectives. To solve it you choose a closed room as your goal and then touch the rooms that prove it; a proven room lights up. Implications are proved inside a hypothetical space where the premise is assumed, and a fork splits a proof into two cases.
The logic is intuitionistic, and the game says so plainly: the law of the excluded middle does not hold, so some rooms never open however you try. Each puzzle you solve is secretly a theorem, and the Trophies page keeps every one with the formula you proved, such as the A, A implies B, therefore B on its title card.
The Daily mode serves one new puzzle every day, the same for everyone, numbered from its start on 25 September 2026. Classic mode deals puzzles one after another at random or at a chosen difficulty from 1 to 8, and How To is a guided sequence that brings in one connective at a time. It is free in the browser with no account, and suits anyone curious about logic as well as players who like abstract, wordless puzzles.
How to play Modus Ponens
- Start with How To if you are new: it introduces one connective at a time.
- Open Daily for the day's puzzle, a map of rooms that each stand for a proposition.
- Choose a closed room as your goal.
- Touch the rooms that prove it; enter an implication's room to assume its premise, and split a fork into its two cases.
- Light the goal room to finish, and find the proved formula in your Trophies.
Screenshots
Tips
- Read each room's outline: its shape tells you which connective it stands for and how it can be proved.
- Do not try to prove a statement from its own negation's failure: the excluded middle does not hold here.
- When a fork appears, prove the goal in both cases separately.
- Use Classic at a low difficulty to learn the connectives before the daily puzzle.
Questions
Do I need to know logic to play Modus Ponens?
No. The How To sequence teaches the rules one connective at a time, and the puzzles are played with rooms and light rather than symbols.
Why will some rooms never open?
The game uses intuitionistic logic, where the law of the excluded middle does not hold, so some classically true statements cannot be proved.
Is there a new puzzle every day?
Yes. Daily mode gives one new puzzle each day, the same for everyone.
Can I play more than the daily?
Yes. Classic mode serves puzzles at random or at a difficulty from 1 to 8.
Ratings and reviews
No ratings yet. Be the first to rate Modus Ponens.
Games like Modus Ponens
Sworn (Mind Loft)
A daily deduction from statements: liars under oath and one thief to name
Morning Mystery
A daily logic mystery solved from facts and statements
LogiCue
Another wordless daily puzzle of working out a hidden rule
MirrorMirror
A minimalist daily grid puzzle solved by planning alone
0h n0
Place red dots so every blue dot sees exactly its number, with a fresh set of grids each day.
3-In-A-Row (BrainBashers)
Colour every square blue or white, with no three alike in a line and every line balanced.
6 Daily Trios
Twelve cards, exactly six Trios, one layout a day.
ABC View (BrainBashers)
Place one A, one B and one C in every line, guided by which letter is seen first from each edge.