Tickle Bomb is a fun puzzle game that runs on practically any platform. The rules are the same as Minesweeper or XBomb, but the tile patterns are far more complex. It can use not just the square grid, or even triangles and hexagons, but octagons and other interesting combinations.
Sudokut is a command line solver for Sudoku puzzles. When supplied with a Sudoku string or file, it returns all possible solutions. It takes approximately half a second to solve a medium force Sudoku by using an efficient algorithm that is guaranteed to find all the solutions. It accepts many options that implement various features (validity check, diff, suggestions, and probing).
MoxQuizz is a multilingual IRC quiz/trivia script for eggdrops which acts as a game master. A question is posted to the channel, and all chatter is searched for the answer. If something matches an answer or an optional regular expression, the user who said it receives a point. Highscores and an allstars table are managed. Users can ask their own questions, too. A large set of German and English questions are provided, but you can easily run MoxQuizz with your own set. There are numerous fun commands like !hug, !roll, and others.