Deductum (with free demo)
In this minimalistic puzzle game, you're given a set of premises and a conclusion, and your task is to use the fundamental rules of logic to formally prove, step by step, that the conclusion follows.
Tutorials introduce you to the world of proofs and the game mechanics. The early problems are simple, but the difficulty gradually increases until eventually you might not even know where to begin. Still, every problem has a solution, and if you think deeply enough, you'll never need to guess!
- Simple controls. No timers. No distractions. Just logic.
- 111 problems to solve, including classic theorems like De Morgan's Laws and the Law of the Excluded Middle
- Sandbox mode: enter any claim (with proposition symbols A–H) and see if you can prove it!
NOTE: To run the MacOS version, double clicking may not work. Instead, try right-clicking the app and choosing 'Open' in the menu and then again 'Open' in the confirmation dialog.
Purchase
In order to download this game you must purchase it at or above the minimum price of $2.50 USD. You will get access to the following files:
Development log
- Version 1.0 released, with free demoMay 18, 2025
Comments
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it would be so convenient if we could also go forward from the premises so we don't have to prove B is true 3 times
You're right, I even had it at some point but decided to remove it to simplify the UI since not many levels seemed to need it. But you're not the first one to comment about it so maybe I was wrong...
The full version does not include:
<-> (implies and vise versa)
-/> (does not imply)
<-
</-
Extra proofs:
A, A -/> B | not B
A, A <-> B | B
not A, A <-> B | not B
Thanks for the comment! I indeed dropped equivalence (<->) because I thought it would clutter the UI without bringing interesting new mechanics. Maybe I'll include it in a future version, though. I'll also add your proof suggestions to a list of possible future additions!
More proofs: A <-> B | A -> B, B -> A
A -> B | A -/> not B
A -/> B | A -> not B
not not A | B
A -> B | B -> A
A <-> B | A -> B, B -> A
A and B | A <-> B
not A and not B | A <-> B
A <-> B | A and B or not A and not B
not A <-> B | not A and B or A and not B
Level ideas:
1.
Premise: A -/> B
Prove: A -> not B
2.
Premises: A -> B, B -/> C
Prove: A -> not C
3.
Premise: A -/> not B
Prove: A -> B
4.
Premise: A <-> B
Prove: A -> B and B -> A
5.
Premise: A and B
Prove: not(A -/> B)
6.
Prove: (not A) -/> A
7.
Prove: (A and A-/> B) -> (A <-> B)