Dimenso is a library for performing dimension-aware calculations in C# and Java. It offers numeric types that have dimensions, expressed in terms of base dimensions M (mass), L (length), T (time), and Q (electric charge). Playing to the strengths of each language, C# types have operator overloads to allow them to be used as numbers, while Java types mimic the BigDecimal with respect to arithmetic methods.
Mindbender is a game which works like Mastermind, but is easier to use. Instead of colors, you use numbers from 1-9. It's a four-digit code you have to solve, as in Mastermind. You can set the number of tries in a separate file or you can use a small setup manager. It's a very small project.