GROWBY GAME - Friday the 13th (Calendar)

Object of the Game

To fill in a calendar month and score points based on the days you choose. Winning the game depends mostly on a player's mathematics skills and mental strategies.

Rules of the Game

The game consists of as many GG-sessions as there are G-players. Each G-player is entitled to initiate exactly one GG-session, in which that G-player is called the GG-initiating-player. This rule ensures that each G-player has equal opportunity in electing a calendar date to his best advantage.

To Begin Each GG-Session in the Game

If you are the GG-initiating-player, take out a blank GG-calendar-month-sheet, throw the G-dice and fill in a day of the month on the sheet, based on the GG-Calendar-Rules.

Once a day has been set on the GG-calendar, the other days of the month can be pre-determined accordingly. All G-players should form a mental picture of this pre-set calendar month throughout the GG-session in order to facilitate the game.

If the calendar month you have initiated contains Friday the 13th, you score an extra 13 bonus points. If you fail to claim your bonus right at the beginning of the GG-session, you miss out. If another G-player declares that observation, he earns those 13 bonus points instead.

Once you are done with (all the initiating procedures and) your turn, pass on to the next G-player to continue with the current GG-session.

When It is Your Turn during the GG-Session in the Game

Throw the G-dice, and based on the GG-calendar-rule, pick a valid day-of-the-month which is still available (i.e. yet unfilled) and write that day in the appropriate space on the GG-calendar-sheet.

If you cannot figure out a valid date which satisfies all the rules, you forfeit your turn to the next G-player.

You score is the number you have chosen. Collect the same amount from the G-bank. The G-money serves to keep track of your score.


To maximize your score, try to choose as late a day-of-the-month (i.e. the highest multiple of the G-number-die) as possible.

To End Each GG-Session in the Game

Due to various limitations (e.g. prime numbers, Fridays), only 23 out of the 31 days-of-the-month can be applied to the game calendar. So the game session is over once those 23 numbers are filled. Start a new game session with a new GG-session-initiator.

To End the Game

The game is over when each G-player has initiated and completed a GG-session. The G-player with the highest score is the winner.

Calendar Rule

Throw the 2 G-dice. The G-shape-die value represents the following:
star Sunday
circle Monday
heart Tuesday
triangle Wednesday
square Thursday
diamond Saturday

NOTE: Friday is not represented.

The day-of-the-month chosen must fit the following criteria:

For Example, the current status of the GG-Calendar-Sheet is as shown below:
star circle heart triangle square diamond star
  3  5  
 16  18   
22    26  28


  • if the G-dice you throw display: circle and 5,
  • then pick Monday the 30th (5x6).


  • if the G-dice you throw display: heart and 3,
  • then pick Tuesday the 24th (3x8).

    Game Accessories

    From the Basic Game Set

    Extra Accessories

    Variation of the Game

    If a G-player, X, forfeits his turn, any other G-player who can come up with a qualifying day-of-the-month can speak up immediately. The first G-player, Y, who raises his hand before the next G-player starts his turn, can call out his number.

    Option I

    If that number meets all the rule, Y can demand his earned score from X.

    Option II

    If Y's number is wrong, he must pay X the same amount of G-money as his called-out number.

    The rest of the G-players, including X, can attempt the call-out again. Repeat Option I or Option II until the game can proceed again to the next G-player in line after X.

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    Disclaimer: This GROWBY© game plan is only the alpha version, to be perfected after our GROWBY Game Design Contest. We sincerely invite your participation - have fun...   
    Updated: 02/11/11
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