We've updated our blog with some designer notes on OpFire in "Warfare in the Age of Madness". The entry discusses OpFire mechanics in general and how we've represented it in Age of Madness. We got the idea for this post from comments on TMP's game design board. We think the topic of OpFire is interesting and central to the periods we all enjoy (20th century and sci-fi gaming).
link
Briefly, the game doesn't include a special or separate OpFire rule.
Instead, elements can spend up to 3 Action Points each turn. It costs 2 AP to shoot, assault, or go on Alert status. Alert status allows an element to react to an enemy action during the enemy's turn. The reaction is resolved after a given enemy action.
For example, an enemy element might spend 1 AP to move and any Alert enemy elements in line of sight can then react. Once an element reacts its Alert status is lost.
That's it.
The game remains fast paced since elements are only shooting once per turn at most and, with no real-time interrupt during movement, it's easy to resolve.
It also recreates overwatch and fire and maneuver tactics while posing interesting tactical challenges to players.
We hope you enjoy the entry and welcome comments or suggestions here or on the blog. We have several projects in the works including WWII and sci-fi versions. We're also about to release some free content for Age of Madness which is mostly based on requests by WAM players. So please do offer your ideas and suggestions as we highly value them and act on them when possible!
PS I cross-posted to WWII since the topic is broadly OpFire which is pertinent to the period. As I note in the entry the game actually started with our 15mm WWII collection and we're working on releasing those rules too.