With apologies to Aesop:

Space and Time were disputing which was the stronger, when a planet came along wrapped in a warm ocean. They agreed that the one who first succeeded in making the planet bear life should be considered stronger than the other.

First, Space gathered atoms from the most distant parts of the Cosmos, but only succeeded in making a few lousy organic molecules, and at last Space gave up the attempt. Then Time gathered creatures from the future, when life had already evolved on the planet, and Space complained that Time had cheated.

And so Time snarled, “All right, smartie—you think it's easy to be me? You try it!”
Then they changed places, and their contest continued.

1. From a standard piecepack, take the following components:
   • All 24 coins.
   • The Sun and Moon suits of tiles for trophies.
   • 6 more tiles of any suit for the board.
2. Flip the board tiles grid-side-up, and lay the tiles 2×3 so that they form a grid of 4×6 spaces. Lay out the trophy tiles so that both players can see the numbers.
3. Flip all coins suit-side-up and shuffle them. Place them on the board in something like the following layout. It doesn't matter where the suits are relative to one another, as long as all the coins in a suit are together in a 2×3 arrangement.
   
4. Now flip the coins so that the numbers are showing. If the four central coins show the same number, it's a misdeal; reshuffle and re-deal the coins onto the board.

Relativity is a two-player game with two roles, Space and Time, and two rounds, Night (Moon tiles) and Day (Sun tiles). Each player plays one role in the first round of the game, swapping coins until the first five trophies are won. Then, in the second round, players reset the board and then take the other role, swapping coins until one has won six trophies or ten trophies are won in total. Space goes first in both rounds.

The object of the game is to collect six trophies for swapping coins on the board and creating “DNA molecules” (special groups of coins). A DNA molecule is represented by a tetromino, or a cluster of four coins of the same value (such as four 5s or four Aces), connected vertically or horizontally, but never diagonally.

Here are some examples of such shapes. The shapes can appear rotated or flipped from the examples, but the basic shapes will be the same.

Space and Time have different powers and swap coins in different ways.

Space has the power of adjacency. Space may swap any coin for any other coin that is orthogonally or diagonally adjacent. For example, in the diagram below, Space may swap the shaded 3 coin with any of the eight coins around it.

In addition, when Space swaps coins, the board “wraps”—that is, the right edge of the board is considered to join up with the left edge, and the top edge with the bottom edge. For example, in the diagram, Space may swap the Null coin on the right edge of the board with the Ace, 2, 5, 3, and Null directly adjacent to it, and also the 5, 3, and 2 on the left edge of the board. Space may swap coins on the edges as if the board were continuous. In particular, Space may swap the coins on all four corners of the board (but only two at a time, of course). Thus, Space may always swap any given coin with eight other coins, even if that coin is on the edge of the board.

NOTE: Space's space-warping powers may only be used for swapping, not for deciding which coins form part of a DNA molecule. DNA molecules do not wrap.

Time has the power of sequence. Time may swap any two coins anywhere on the board whose numbers are next to each other in sequence. For example, Time may swap the shaded 3 coin in the diagram below with any of the four 2 coins or four 4 coins on the board. Null coins are considered to be 0, and Aces to be 1, so the sequence runs N, A, 2, 3, 4, 5. Time's time-warping powers wrap the sequence, so a 5 may be exchanged with a 4 or a Null, and a Null may be exchanged with an Ace or a 5. Thus, Time may exchange any given coin with eight others as well.

NOTE: You may not reverse the move your opponent has just made, even if you normally could.

When you create a DNA molecule, take the corresponding trophy for that number in the current round. For example, if you make a DNA molecule from four 3 coins during the Day round, show it to your opponent and take the 3 of Suns tile. Once someone takes a trophy for a number, no one may score that number again during that round. If you are clever enough to make two DNA molecules (or more) on the same swap, you may take all the trophies for the numbers you matched up.

When five trophies have been won and only one trophy remains in the first round, set it aside and do not score it, then reset the board, switch roles, and play the second round.

When only one trophy remains in the second round, again set it aside and do not score it.

The game ends as soon as one player gains six or more trophies or when the fifth trophy is won in the second round. The winner is the player who gains the most trophies. If each player has five, the winner is the player who played Space during the first round.

Copyright 2011 Marty Hale-Evans and Ron Hale-Evans. This work is licensed under the Creative Commons Attribution-ShareAlike 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-sa/3.0/ or send a letter to Creative Commons, 171 Second Street, Suite 300, San Francisco, California, 94105, USA.