Diplomacy is the Avalon Hill Game Company's trademark for its game of international intrigue, which game is copyright 1976 by Avalon Hill. Avalon Hill belongs to Hasbro.
The order notation in this document is as in DATC, with the following additions for multiversal time travel.
Germany 2:0 A Munich supports A Munich 1:1 - TyroliaThe order here is for Army Munich in 2:0. The move being supported is for Army Munich in 1:1 to move to Tyrolia in 1:1.
A unit that moves into its own immediate past causes the timeline to fork.
Germany 0:0 A Munich hold Germany 1:0 A Munich - Tyrolia 0:0
A Munich 1:0 moves to Tyrolia 0:0. The main timeline advances to 2:0 with an empty board. A forked timeline advances to 1:1 with armies in Munich and Tyrolia.
A unit that supports a move that previously failed in the past, such that it now succeeds, causes the timeline to fork.
Austria 0:0 A Tyrolia hold Germany 0:0 A Munich - Tyrolia Austria 1:0 A Tyrolia hold Germany 1:0 A Munich supports A Munich 0:0 - Tyrolia 0:0
With the support from A Munich 1:0, A Munich 0:0 dislodges A Tyrolia 0:0. A forked timeline advances to 1:1 where A Tyrolia 0:0 has been dislodged. The main timeline advances to 2:0 where A Munich and A Tyrolia are in their initial positions.
A unit that attempts to move into the past, but is repelled, does not cause the timeline to fork.
Austria 0:0 A Tyrolia hold Germany 0:0 A Munich hold Austria 1:0 A Tyrolia hold Germany 1:0 A Munich - Tyrolia 0:0
The move by A Munich 1:0 fails. The main timeline advances to 2:0 with both armies in their initial positions. No alternate timeline is created.
A unit that supports a move that succeeded in the past and still succeeds after the additional future support does not cause the timeline to fork.
Germany 0:0 A Munich - Tyrolia A Bohemia hold Germany 1:0 A Tyrolia hold A Bohemia supports A Munich 0:0 - Tyrolia
Both units in 1:0 continue to 2:0. No alternate timeline is created.
In this test case, a unit elsewhere on the map moves into the past to cause a timeline fork. Once there are two parallel timelines, a support from one to the head of the other should not cause any forking, since timeline forks only occur when the past changes, not the present.
Austria A Tyrolia 2:0 hold A Tyrolia 1:1 hold Germany A Munich 2:0 - Tyrolia A Munich 1:1 supports A Munich 2:0 - Tyrolia
A Munich 2:0 dislodges A Tyrolia 2:0. No alternate timeline is created.
Following 3.A.5, a cross-timeline support that previously succeeded is cut.
Germany A Munich 2:0 - Tyrolia A Munich 1:1 supports A Munich 2:0 - Tyrolia Austria A Tyrolia 2:0 holds A Tyrolia 1:1 holds Germany A Tyrolia 3:0 holds A Munich 2:1 holds Austria A Tyrolia 2:1 - Munich 1:1
Cutting the support does not change the past or cause a timeline fork.