Constraint Lab
Logic grids, ordering problems, truth puzzles, and information-gain challenges that build from guided to difficult.
- Planned: 40 puzzles
- Worked answer paths
- Printable and screen formats
Puzzle collections and free sampler
Play four free explained challenges now. Paid printable collections are still in editorial review and are not available for purchase.
What is available now?
The four-problem sampler is available free. Pricing and checkout will appear only after the paid files, answer keys, licence terms, and payment flow have been tested.
Think Sideways
Lateral-thinking scenarios designed to expose assumptions without relying on arbitrary trick answers.
- Planned: 36 scenarios
- Progressive hint cards
- Discussion prompts
Better Decisions
Real-world cases for prioritization, root cause analysis, bottlenecks, and evidence planning.
- Planned: 24 cases
- Facilitator notes
- Reusable worksheets
Play the free four-problem sampler
Each challenge opens with a hint, explanation, and transferable lesson.
Find the heavier coin
Nine identical-looking coins include one heavier coin. Using a balance scale only twice, how can you always find it?
Three switches, one visit
Three switches are outside a closed room. Exactly one controls a traditional incandescent bulb inside. You may operate the switches however you like, but may enter the room only once. How do you identify the correct switch?
Measure 45 minutes with two ropes
You have two ropes. Each takes exactly 60 minutes to burn, but neither burns at a uniform rate. With a lighter and no clock, how can you measure exactly 45 minutes?
The meeting room bottleneck
A team says it needs more meeting rooms because every room is booked. Booking data shows that 38 percent of reservations are never used. What should the team test before paying for more space?
What every paid collection must include
A collection will not be released until every closed-answer puzzle has been checked for uniqueness, every open case states how answers are evaluated, the difficulty curve has been playtested, and the answer key explains the reasoning rather than only naming the result.
Browse all free logic puzzles and brain teasers while the collections are in review, or read how a fair puzzle is designed and checked.
Licensing plan
Personal and classroom licences will be described in plain language before checkout. Teams that need internal workshop use can contact hello@problem.so. No recurring subscription will be added without an explicit price and cancellation flow.