Play by geohash

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PBGH (Play By GeoHashing) games are games in which you play by visiting hashpoints for your moves.

The concept is modeled off of Play By Mail or Play By E-Mail games, in which certain games (particularly chess) were played by people mailing their moves to each other. This allowed people who lived a long ways away from each other to play each other. For play by geohashing games, it provides some added fun and friendly competition into geohashing. These games can be expected to last a long time, since only one move can be made per player per day, and games will typically last many turns.

PBGH games should include the following:

  1. Players should be able to transport the game to the hashpoint, and be able to take a picture of the move being made or having been made.
  2. Either the coordinates, or the terrain/locality of the geohash points visited should influence how the game is played.
  3. A move should only be possible if the coordinates are reached.
  4. Fun! Above all, if it doesn't increase the fun you have with geohashing, then there is no point to it!



Your visited hashpoints (more specifically, which centicule they fall into) translate into missile shots at your enemy's ships.

A1 is always the SW corner of the graticule, J10 is always the NE corner, no matter where in the world the people live.

Each player has 5 ships to place in a straight line either vertically or horizontally (no diagonal ships)

  • 1 5-length ship
  • 1 4-length ship
  • 2 3-length ship
  • 1 2-length ship

Calculating shot locations: You can use this handy-dandy template to do it for you, look at the table below:

Longitude -180 through -30 -30 through -0 0 through 180
Northern hemisphere Today's battleship location is:  not yet announced Today's battleship location is: H


Today's battleship location is: C


Southern hemisphere Today's battleship location is:  not yet announced Today's battleship location is: H


Today's battleship location is: C


If you want to do the calculations yourself, because you don't trust template witchery:

Use the signed offsets generated by the geohashing algorithm:

  • Examples:
    • .6532 lat, -.0683 lon
    • -.9542 lat, .3584 lon

1. Multiply by 10, and take the integer part, preserving the negative sign, even if 0

  • 6 lat, -0 lon
  • -9 lat, 3 lon

2. If the number has a negative sign, add 9

  • 6 lat, 9 lon
  • 0 lat, 3 lon

3. Add 1

  • 7 lat, 10 lon
  • 1 lat, 4 lon

4. The lat is the number, the lon points to that letter of the English alphabet

  • J7
  • D1

There is also a template which will calculate the battleship coords for you:


  1. Turn Length
    1. Players should negotiate a length of time (typically in days), after which a player forfeits their turn.
    2. A time of 0 days is an asynchronous game. Every visited hashpoint counts as a shot.
  2. Players should negotiate on a start time.
  3. Players should bring a battleship board to the hashpoint. This battleship board should have the current shot being taken at a minimum. Having the full history of shots is preferred, however.


  • 0-4 hits: boat with a person on it, a missile hitting water off the side of it, person on deck laughing
  • 5-10 hits: boat with a small hole in the side, and a bit of fire, person on deck calmly commanding troops
  • 11-16 hits: boat with two holes, and a decent amount of fire, person on deck panicking
  • 17 hits: boat completely engulfed in flames, starting to sink, person in dinghy escaping

Now to get the ribbons actually made.

Pilot test

  • Asynchronous
  • Boards shall be drawn by the end of day 2010-04-22. First eligible points start at 2010-04-23.
  • relet and aperfectring, the creators, are playing this pilot game
  • Both relet and aperfectring got their first shots off on the same day, on just the third day of the contest!
  • aperfectring finally managed to visit a second geohash!
  • relet got the first hit on 2010-11-17!
Hit: Miss:
Attempt: Sunk:

Aperfectring's "Guesses"

Aperfectring's apt admiral shall abolish all opposing aquatic adversaries.


Relet's "Guesses"

Relet's really rather recognizable regions of residence remain resolved.


Calvinball (proposed)

Should we call it "nomic" or "1000 blank white achievements"?

Claim the Calvinball achievement when you as an individual or a group have reached a geohash while following all the rules below. Then add a rule to this list. The game continues, until it becomes impossible to continue following the rules. Any player may at any time claim that it it is impossible to follow the rules, in which case the player who set up the last rule must prove the contrary. If they are able to do so, the game continues, and they add another rule to this list. If they are unable to do so, their achievement is replaced by the "Lost at Calvinball achievement" and the rules are reset to only the first rule. No rule may ever be reproposed. All other players get to claim a "Won at Calvinball achievement".

  • Rule 1: All players must wear a Calvinball mask. No one questions the masks.

Baseball (proposed)

This is a work in progress, and comments or suggestions are welcome on the Talk Page.


  • Choose up two sides, individual or evenly matched teams.
  • Each player specifies a home graticule, and chooses an area to be their "strike zone".
Suggestion: This should be an easily-identified area, e.g. the northeast quadrant of your home graticule. The area of a half-graticule is ideal, but a 20 mile / 50 km radius may also be agreed upon (since you can get a distance from online maps
You can have a strike zone that crosses parallels/meridians, but should overlap your home graticule unless you're a masochist. :-)
  • This area also serves the "infield", for the purposes of fielding (see below)
  • The sides should agree on a neutral referee or other means for resolving some results.
  • The sides should decide on a day for the game to begin.


  • One side is batting, and decide what order they'll take turns "batting". The entire other side is "fielding" until three outs are made.
  • Each day's geohash is a pitch. If it's in your strike zone and you don't reach it, that's a called strike. If it's in your home graticule but not in the strike zone, it's a ball. (That's why the strike zone is not the entire graticule). Three strikes and you're out, four balls and you're "on base" (or you just pass your turn?).
  • An expedition constitutes a swing. You are not limited to expeditions in your "strike zone". A successful geohash puts the ball "in play" (see below). An unsuccessful geohash expedition is a swinging strike.

Ball in play

  • When the "ball" is put in play, the next day's geohash specifies where the ball was hit.
  • If the in-play geohash is unreachable for the batter, it's a foul ball and the at-bat resumes the next day (don't add a ball or strike).
  • If the in-play geohash is in the batter's strike zone/infield, then it's a ground ball. If a fielder reaches the geohash before the batter does, the batter is out. If the batter reaches it first, they're on "first base".
  • The batter can try to advance more than one base by trying to reach other locations. Extra bases must be reached before midnight (local time).
    • Second base is 0.5 degrees north or south, whichever is within your home graticule.
    • Third base is 0.5 degrees east or west, whichever is within your home graticule. You run the bases clockwise or counterclockwise, depending on where you started (is that confusing?)
    • Home is 0.5 degree in the opposite direction that you "ran" to second base. (at this point you've visited four points of a rectangle.)
      • Extra points for style if you post a video of yourself sliding into home ;-)
  • If the in-play geohash is outside the batter's infield, then it's a "fly ball". The fielder(s) have all day to reach the geohash to make an out. The batter can advance bases as above, but there is no race.
  • Runners on base stay on base until the end of the inning. They advance when the batter advances (you're not responsible for reaching geohashes once you're on base!)

Nerdy baseball-y stuff

  • If a ground out is made, the lead runner is removed, not the batter.
  • The batter's infield decides whether an in-play ball is a grounder or a fly ball. Just because it's close to the fielder's home, doesn't mean it's a grounder, it just means you're in effect positioned in the outfield.

Things that still need to be addressed

  • Ground balls are essentially a race, which in earlier discussions we wanted to avoid. Maybe all in-play geohashes should use the fly-ball rule?
  • An inning, for both sides to get a full complement of at-bats, could extend for over a month. Hence four "balls" = your at-bat is over but no "base runner". Is there a way to shorten it? Maybe just a limit of seven "pitches"?
  • Can the batter declare "sacrifice" to allow existing base runners to advance in case of an out? They should make the declaration before their at-bat starts (before geohash release time), and they ought to be able to change their mind from one day/pitch to the next.

GeoDarts (proposed)

The graticule is divided into an agreed-upon grid, and each successful expedition is considered a "hit". An example dartboard is shown below, although players may also define their own depending on the specifics of their own graticules.


Variation 1 (turn-based):

  • Each player alternates weeks, with their designated week representing their turn. Exceptionally busy players may choose to alternate months. For cases with more than two players, players take turns in a specified order.
  • During their turn, any successful expeditions score points based on their locations. Unsuccessful expeditions score nothing. (Players may decide on a distance that counts as "successful," such as "within 100m of the point.")
  • Each expedition is a dart, so no more than 3 expeditions per turn may score points, and point-scoring expeditions must be declared ahead of time. Making more than 3 expeditions in a turn and choosing the best three at the end is not allowed.
  • At the end of each turn the points scored are subtracted from the player's total. The object is to reduce the score to zero (called "checking out"). Official games of darts check out starting from 501, but that could make for exceptionally long geohash dart games, so players are encouraged to pick an agreed-upon value before the game starts.
  • If the points scored during a turn would reduce the score to 1 or something less than zero, the turn is "bust" and points from that turn are lost. This is not likely to happen in the geohash version, as players either score a specific number of points or don't on any given day, and can choose not to mount an expedition if the points would bust the turn.
  • In the official darts rules, checking out must be done on a double. Since players may have to wait a long time for a point in the double ring to appear (odds of checking out on a double are 0.55% in the example board shown), this rule is optional in the geohash version.

Variation 2 (melee):

  • Rules are the same as the turn-based version, except that there are no turns. Each player may go for the day's geohash point at any time.
  • The first player to check out wins. This could conceivably result in a race for the last point, but only if the players happened to have the same number of points left on that day. Unless the players all went for and achieved the same points in sequence, this is unlikely.

Notes on board and turn definition:

  • If players are operating in two different graticules, more than one board may be defined. In order to ensure fairness, the areas of each box (as a percentage of total graticule area, in the case of significantly different latitudes) should be equal on the two boards.
  • Boards may be defined to exclude restricted areas, water, etc. so that more points are available to the players.
  • Players may choose to locate the various point values in order of difficulty in the graticule; the 1-point box may be in the center of a public park, while the triple 20 point box may be at the peak of a mountain. The example board given below was defined in the order of an official dartboard, proceeding clockwise around the face from the top, so values will be more or less randomly distributed around the graticule.
  • Instead of alternating weeks/months, players may choose to simply set a time limit for each turn. Once a player has "thrown" 3 darts (mounted 3 expeditions, successful or not), their turn is over and the next player's turn starts. If the player does not "throw" 3 darts by the time limit, then that player forfeits the remaining darts in that turn and the next player's turn starts.

Example Dartboard

This is roughly based on the layout of an official dartboard. The decimals on the edges represent the limits of each sub-box within the graticule. For example, if the day's geohash decimals were (0.179468, 0.861536) then the point would fall in the (0.00-0.26, 0.85-0.90) box and a successful expedition would score 9 points. The bull's eyes may be arbitrarily placed to coincide with interesting places in the graticule, such as within a city's limits or in a specific state park. Keep in mind that the smaller the bull's eyes are defined, the less likely they are going to be available for throwing a dart at. The Inner Bull defined below has a 0.55% chance of hitting, meaning it will be available for an expedition, on average, once every 6.5 months or so.

0.00-0.26 0.26-0.37 0.37-0.63 0.63-0.74 0.74-1.00
20 Double 20 Triple 20 0.00-0.05 Latitude
1 Double 1 Triple 1 0.05-0.10
18 Double 18 Triple 18 0.10-0.15
4 Double 4 Triple 4 0.15-0.20
13 Double 13 Triple 13 0.20-0.25
6 Double 6 Inner Bull (50) 6 0.25-0.30
10 Double 10 Triple 10 0.30-0.35
15 Double 15 Triple 15 0.35-0.40
2 Double 2 Triple 2 0.40-0.45
17 Double 17 Triple 17 0.45-0.50
3 Double Outer Bull (25) Triple 3 0.50-0.55
19 Double 19 Triple 19 0.55-0.60
7 Double 7 Triple 7 0.60-0.65
16 Double 16 Triple 16 0.65-0.70
8 Double 8 Triple 8 0.70-0.75
11 Double 11 Triple 11 0.75-0.80
14 Double 14 Triple 14 0.80-0.85
9 Double 9 Triple 9 0.85-0.90
12 Double 12 Triple 12 0.90-0.95
5 Double 5 Triple 5 0.95-1.00


Possible achievements related to this game:

  • GeoDart Champion Geohasher won a game of GeoDarts.
  • GeoDart Participation Ribbon Geohasher played an entire game of GeoDarts to completion.
  • Bull's Eye! Geohasher scored a Bull's Eye in a game of GeoDarts at hashpoint.
  • Triple! Geohasher scored a triple in a game of GeoDarts at hashpoint.
  • Double! Geohasher scored a double in a game of GeoDarts at hashpoint.
  • Dart Inception Geohasher won a game of darts at hashpoint where they also won a game of GeoDarts.
  • GeoDart Bust Geohasher purposely busted and forfeited all points for this turn just to get this achievement.