Movement
When you take the Crawl, Dash, Run, Step, or Stride actions, you move a distance based on your roll and base speed.
Most creatures have a speed equal to their Size -5 unless noted otherwise.
When you Stride (1 action), you roll 1d20 + Speed and move up to that many yards/meters. If you get a 0 or less, you don't move but fall prone instead (Acrobatics as reaction negates).
When you Step (1 action), you move half this distance but foes have disadvantage on reactions they make against you as a result of this movement. If you have Mobility you make Acrobatics roll as part of doing this and impose penalty to reactive attacks against you for moving equal to 1/5 your result.
When you Dash (2 actions) you move triple this distance but can only move in a straight line and must make acrobatics roll to avoid falling prone if you move over difficult terrain.
When you Run (3 actions) you move five times this distance but can only move in a straight line and must make acrobatics roll to avoid falling prone if you move over difficult terrain.
POSITIONING
Unless noted otherwise...
Your REACH in yards/meters is equal to your size.
Your SPEED in action scenes is STR + DEX + SIZE.
Your SPEED in exploration scenes is CON + WIS + SIZE.
Your SPEED in social scenes is INT + CHA + 1/2 level of highest level influence.
Size 4-5 creatures take up 2x2 spaces. Size 3-2 creatures takes up 1x1 space. You can fit up to four size 1 creatures in a single 1x1 space.
DEX vs. AGI