| CellFighter: Shareware game based around an extension of the game of life. |
| IBM Research: Ponder This: Monthly logic and math puzzles set by IBM researchers with solutions. |
| Jim Loy's Puzzle Page: Classic and original puzzles. |
| Kakuro-san: Providing graded Kakuro puzzles every day, plus old puzzles. |
| Leisure Ideas: Puzzles: Some mathematical puzzles with answers and/or a hint. |
| Mathematical Jigsaw Puzzles: Information on polyominos and square puzzles. |
| Monty Hall Game: JavaScript example of the Monty Hall Game. This game demonstrates the real (empirical) affect of statistics. [Does not display correctly in all browsers.] |
| Perplexus: A forum and collection of brain teasers, logic problems, math problems, paradoxes, science games, probability, riddles, and geometric shapes. The puzzles are searchable and categorized, most have solutions. |
| Quick Logic Puzzles: Use the clues provided to deduce the correct sequence of numbers in the hidden code. |
| TechInterview: Answers to technical interview questions, programming problems, and brain teasers. |
| The Monty Hall Problem: A probability theory puzzle with solutions. [English and German.] |
| The Puzzles of Oscar: Contains puzzles and games with solutions. |
| The Truth Tree's Math and Logic Board: Collection of math and logic puzzles ranging in levels of difficulty. |
| Two Envelope Paradox - Solution: Claims that the two envelope paradox comes from the incorrect use of probabilities. |
| WU Forums: Discussion board hosted at Berkeley with talk about a variety of solved and unsolved brain teasers. |
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