I have a somewhat detailed hypothetical example below, as I'm trying to make sure our group is playing FoF right
In the example below, I'm writing from my perspective as I understand the rules. I'd like to hear if my interpretations are correct.
In this high-quality and professional pen outline (certainly NOT drawn with a Where's Waldo? book as my solid writing surface because nothing else was at hand), the square shapes are one story buildings. For this example, let's assume that all the units are D8 quality regulars. Units A, B, and C have the Initiative. Unit B is on Overwatch.
Unit A declares that it will move to point Y and engage enemy unit 2 hiding behind a building. The noninitiative Units 1 and 3 declare that they will both React with Fire to Unit A at point X and Unit 2 will also react with Fire at point Y. Unit B declares Overwatch Fire against Unit 1. Unit C declares Opportunity Fire at Unit 2.
Unit A declares that it will pause at point X to return fire at Unit 1 and then continue to point Y.
The reaction rolls: Unit 1 rolls an 8. Unit 3 rolls a 1.
Unit A rolls a 7. Unit B rolls a 7 but gets a modified 8 because of being on Overwatch.
I understand the rundown to occur like so, in this order:
Unit B fires at Unit 1 with no effect.
Unit 1 fires at Unit A with no effect.
Unit A fires at Unit 1 with no effect.
Unit 3 failed its Reaction check (rolled a 1) so can't react to Unit A at point Y (and it can only return fire for the rest of the turn).
Unit A continues moving along its arc to Point Y, but moves 1" less because of its return fire against Unit 1 earlier. Let's say that this reduced move still gets it to a LOS to Unit 2, its original target.
Reaction checks again:
Unit 2 rolls a 5.
Unit C (Opportunity Fire) rolls a 1.
Unit A rolls a 4.
Unit 2 gets to fire at Unit A.
Unit A (assuming it's alive) returns fire at Unit A, but with 1 less die.
Unit C fires last, at Unit 2.
Initiative units are done.
The only Noninitiative unit that can do anything is Unit 4, as the other units have fired or failed reaction checks this turn.
Unit 4 moves to Point X to engage Unit A.
Unit A declares that it React with Fire at point X (where Unit 4 comes into LOS). Unit C cannot React because it failed its Reaction check earlier and is not being directly engaged so thus can't return fire. Unit B, on overwatch, will also engage Unit 4 at point X.
Unit 3 cannot react to anything because of its failed Reaction test earlier. Units 1 and 2 react to Unit A's fire. For this example, I don't think its necessary to go through their reaction tests, other than to say that Unit B will fire with 1 fewer die, Unit A with 2 fewer, and Units 1 and 2 with 1 fewer.
Thanks for reading this far! I want to make sure I'm doing this right.