As I’ve mentioned, I’ve been recently codifying my rules for Simultaneous Initiative. I realized that players may want to know definitively how simultaneous movement works. This is what I have:
Simultaneous Movement
In most cases, it is not necessary to worry about the movement of creatures. This is usually because many players move to a location and stop or the answer is obvious.
For example, Lydia, with a move of 30, and an orc, with a move of 20, are 25 feet apart and move towards each other. Since the orc’s move is 2/3 of Lydia’s, she moves 3 spaces forward and the orc two.
At rare times, though, it may be necessary for a DM to determine exactly how each creature moves (as when two creatures are contesting the location of a space). In those cases, the DM refers to the following chart:
Simultaneous Movement and Initiative Modifiers

Reading the Chart:
A move action is a half-round action divided into segments of half a second each. A ‘space’ is a 5 by 5 square.
For each segment above, the creature with the listed speed may move into the next space if its value is underlined.
If two or more creatures attempt to enter the same space in the same segment, roll initiative and modify it with the value listed above. The winner gains the space. The loser does not move and if it wishes to move in the next segment, treats that segment as segment 1 (but, of course, only up to the number of segments left in the half-round). Note: This roll is only for the current move initiative.
If a creature moves diagonally then at each even numbered diagonal space it moves to, subtract 6 from its initiative.
Example: As earlier, except Lydia and the orc are 30 feet apart. In segments one and three, both move 5 ft. In segment two, Lydia moves but not the orc. In segment four, they each get to move but the move would place them in the same space. Initiative is rolled with Lydia getting +6 to the roll and the orc +4.
If a creature has a speed greater than 30, then it is considered to get the benefit of the 30 row for each full 30 points of move it has and the benefit of the row equal to the remainder after subtracting each 30 points (modulus). If it contests a space, it automatically wins initiative if its move speed is 30 or more than its highest opponent. For each space it moves subtract 6 from its initiative after the move.
Example: A creature with an 80 speed gets to move 2 spaces in each segment for 60 points of its move. The remaining 20 would allow an additional space in segments 1, 3, 4, and 6. It cannot lose initiative in the first space it moves to anyone with 50 or less speed. Likewise, it cannot lose initiative in the second space to anyone with 20 or less speed. If the second space is contested by someone with 30 speed, it would get +10 to its initiative. If that space were its second diagonal move, its initiative would be +4.
The ‘Technical’ Version
1. Determine each creature’s speed.
2. For each space the creature wishes to move to, add its move rate, then:
a. If its current rate is greater than 15, the creature may move to the space. Subtract 30 points from its current rate (even if a negative value results).
b. If its current rate is 15 or less, the creature does not move.
3. If the space is contested by one or more creatures, divide each creature’s initial rate for the segment by 5 to find its initiative modifier. Roll initiative. The winner gains the space. The loser does not move, and its current rate drops to zero.
If the space is an even numbered diagonal space, reduce initiative by six.
Simultaneous Movement
In most cases, it is not necessary to worry about the movement of creatures. This is usually because many players move to a location and stop or the answer is obvious.
For example, Lydia, with a move of 30, and an orc, with a move of 20, are 25 feet apart and move towards each other. Since the orc’s move is 2/3 of Lydia’s, she moves 3 spaces forward and the orc two.
At rare times, though, it may be necessary for a DM to determine exactly how each creature moves (as when two creatures are contesting the location of a space). In those cases, the DM refers to the following chart:
Simultaneous Movement and Initiative Modifiers
Reading the Chart:
A move action is a half-round action divided into segments of half a second each. A ‘space’ is a 5 by 5 square.
For each segment above, the creature with the listed speed may move into the next space if its value is underlined.
If two or more creatures attempt to enter the same space in the same segment, roll initiative and modify it with the value listed above. The winner gains the space. The loser does not move and if it wishes to move in the next segment, treats that segment as segment 1 (but, of course, only up to the number of segments left in the half-round). Note: This roll is only for the current move initiative.
If a creature moves diagonally then at each even numbered diagonal space it moves to, subtract 6 from its initiative.
Example: As earlier, except Lydia and the orc are 30 feet apart. In segments one and three, both move 5 ft. In segment two, Lydia moves but not the orc. In segment four, they each get to move but the move would place them in the same space. Initiative is rolled with Lydia getting +6 to the roll and the orc +4.
If a creature has a speed greater than 30, then it is considered to get the benefit of the 30 row for each full 30 points of move it has and the benefit of the row equal to the remainder after subtracting each 30 points (modulus). If it contests a space, it automatically wins initiative if its move speed is 30 or more than its highest opponent. For each space it moves subtract 6 from its initiative after the move.
Example: A creature with an 80 speed gets to move 2 spaces in each segment for 60 points of its move. The remaining 20 would allow an additional space in segments 1, 3, 4, and 6. It cannot lose initiative in the first space it moves to anyone with 50 or less speed. Likewise, it cannot lose initiative in the second space to anyone with 20 or less speed. If the second space is contested by someone with 30 speed, it would get +10 to its initiative. If that space were its second diagonal move, its initiative would be +4.
The ‘Technical’ Version
1. Determine each creature’s speed.
2. For each space the creature wishes to move to, add its move rate, then:
a. If its current rate is greater than 15, the creature may move to the space. Subtract 30 points from its current rate (even if a negative value results).
b. If its current rate is 15 or less, the creature does not move.
3. If the space is contested by one or more creatures, divide each creature’s initial rate for the segment by 5 to find its initiative modifier. Roll initiative. The winner gains the space. The loser does not move, and its current rate drops to zero.
If the space is an even numbered diagonal space, reduce initiative by six.