‘O’ group has three steps to hit something – spot, hit, save – can it be simpler?

As my recent post on Three dimensions of game design: Simulation, Playability, Abstraction shows, I’m allergic to multiple steps to resolve a single action during game. I’m allergic because multiple steps slows the game down. ‘O’ Group has three steps to resolve each shooting action by a rifle platoon – spot, hit, save. Of course, the is the traditional link from hit to save as well, but there is also a link between the first step (spot) and the last (save) that you have to remember – and those links add cognitive load and take time. So I wanted to explore simpler rules that achieved a similar effect but with less steps. I can’t match the results exactly but I can get pretty close with a single to hit step, dropping spot and save.

Warning: Do not read this post unless probabilities in game design are your thing.

The ‘O’ Group shooting rule for a Rifle Platoon

In ‘O’ Group a shooting action has three steps, so three dice rolls. Attacker rolls “Spotting dice” (p. 50-51). Attacker then rolls “Firepower dice” to hit in direct fire with small arms (p. 56-58). And finally the defender rolls a “Morale Test” – effectively a saving throw (p. 58, 81). Actually there is a fourth roll (“Infantry Platoon Rout Test”, p. 83), to prevent routing when a rifle platoon is down to a single section, but that only happens in a limited set of situations so I’ll ignore it.

Spotting dice:
Targets in the open are automatically spotted. If the target is in Cover / Buildings then roll 1d6 for spotting with a 1-3 meaning the target is Obscured and a 4+ meaning spotted. Usually this roll is made at the same time as the to hit roll, but using a different coloured die. Conceptually, however, it is a separate step.

Firepower dice:
To hit, a rifle platoon has 2d6 firepower per section so 6d6 in total. The platoons scores a hit on each 4+.

Morale test:
Confident and Regular in cover get a morale test with 1d6 for each hit – a standard saving throw mechanism. The score to save depending on the spotting roll. If Obscured they save on 3+ and 4+ if Spotted.

I did some quick maths to combine the spotting dice and morale tests, and found the following probabilities:

Chance of Obscured & successful Morale = 1/2 x 2/3 = 2/6 = 4/12 (33%)
Chance of Obscured & failed Morale = 1/2 x 1/3 = 1/6 = 2/12 (17%)
Chance of Spotted & successful Morale = 1/2 x 1/2 = 1/4 = 3/12 (25%)
Chance of Spotted & failed Morale = 1/2 x 1/2 = 1/4 = 3/12 (25%)
Total chance of successful Morale = 7/12 (58%)
Total chance of failed Morale = 5/12 (42%)

The average number of dice rolled for a rifle platoon is 10d6, i.e. Spotting (1d6) + Firepower (6d6) + Morale (3d6 on average). It can be more or less depending on the hits, but lets go with 10d6.

The average number of hits is 1.2, i.e. 6 x 1/2 x 5/12 = 30/24. That means, on average, a rifle platoon will inflict 1.2 hits on a Confident and Regular target in cover, after doing the spotting roll, the firepower roll and the morale test.

Rifle Platoon: Alternatives with less buckets of dice

Like I said, I don’t like mechanisms with require multiple steps (multiple dice rolls) to resolve a single action. Personally I like to Abstract away the detail. I’m not interested in simulating each step (in this case spotting, hitting, response to being hit), I’m only interested in the result of the action (in ‘O’ Group that is “shock” and section removal). Focussing on the result, not the journey to the result, speeds up game play.

So I explored alternative mechanisms that eliminate both the spotting roll and morale test from the shooting action. My thinking is I only need the hit roll.

Alternative 1:
2d6 per section so 6d6 but hit on 5+ not 4+. Average number of hits = 2.0, only 6d6 rolled and no dependency between steps.

Alternative 2:
1d6 per section so 3d6 and hit on 4+. Average number of hits = 1.5, only 3d6 rolled and no dependency between steps.

Alternative 3:
2d6 per section so 6d6 but hit on 6+ not 4+. Average number of hits = 1.0, only 6d6 rolled an no dependency between steps.

The table below has all the gritty detail behind the standard ‘O’ Group rule and the three alternatives.

Rifle Platoon shooing into Cover
Rule Sub-rule or calculation ‘O’ group standard Alternative 1 Alternative 2 Alternative 3
Spotting roll Spotting dice 1d6
Spotting result 1-3 Obscured; 4+ Spotted
Hit roll Dice per section 2d6 2d6 1d6 2d6
Firepower dice 6d6 6d6 3d6 6d6
Hit on score 4+ 5+ 4+ 6
Average hits 3 2 1.5 1
Morale test Average number of morale dice (matching average hits) 3d6
Passed morale test on score 3+ if Obscured; 4+ if Spotted
Summary statistics Steps to resolve action 3 (Spotting, Hit, Morale) 1 (Hit) 1 (Hit) 1 (Hit)
Average number of dice rolled 10d6 6d6 3d6 6d6
Average number of hits 1.2 2.0 1.5 1.0

It happens that in the ‘O’ Group shooting action, there are both more steps and more dice than the alternatives I’m outlining. But, to be clear, my objection is not the number of dice. I’m okay with buckets of dice. My objection is the number of steps and associated cognitive load and slower play.

Alternative 1 is probably too generous for the shooter, with an average of 2 hits rather than the standard 1.2 hits.

Personally, I’d find either alternative 2 or 3 both simpler/faster as a game mechanism and close enough in terms of result. Neither are exact match the current rule in terms of outcome (1.2 hits on average), with Alternative 2 having an average of 1.5 hits and Alternative 3 having an average of 1 hit per shooting action by a rifle platoon. But close enough I reckon.

Machine gun platoon

I did the maths for a machine gun platoon as well.

MMG Platoon has 6d6 firepower dice per section so 12d6 in total. Hit on 4+.

Average number of hits is 2.4, i.e. 12 x 1/2 x 5/12 = 60/24

Alternative 1:
6d6 per section so 12d6 but hit on 5+ not 4+ with average number of hits = 4.0

Alternative 2:
3d6 per section so 6d6 and hit on 4+ with average number of hits = 3.0

Alternative 3:
6d6 per section so 12d6 but hit on 6+ not 4+ with average number of hits = 2.0

Again, alternative 1 is too generous, particularly as machine gun platoons in ‘O’ Group are already quite lethal. But I’d say alternatives 2 or 3 is good enough, and they have the advantage they’ll be simpler/faster.

So what?

Would I introduce this as a house rule for my ‘O’ Group games? Probably not. This is one single optimisation amongst a whole bunch of interrelated rules and this tweak probably breaks something else in ‘O’ Group. Perhaps a lot of something elses.

Ultimately this was a thought experiment. Kind of answering the question, if I’d designed the game, would I have done it differently? Would I have made different choices and balance the Simulation, Playability, and Abstraction differently?

Well, yes. As I said in Three Dimensions of Game Design:

  • I’m more interested in speed of play than detailed game mechanics (playability versus concrete level of abstraction).
  • I’m more interested in accuracy of combat simulation than precision of combat simulation (simulation versus concrete level of abstraction).

[If you’re interested in the distinction between accuracy and precision, then check out Accuracy vs Precision in Estimation. It is from a different domain (software estimation) but the distinction applies in game design equally as well.]

8 thoughts on “‘O’ group has three steps to hit something – spot, hit, save – can it be simpler?”

  1. I do this sort thing all the time. I reverse engineered the bizarrely obscure CRT in “Rommel” and discovered you could replicate the spread of results by throwing 2D6 against the unit morale rating. Go for it, keep it as simple as possible.

  2. I’m all for abstraction and elegance in game design so I appreciate the whys and wherefores of what you’re exploring here. Focusing on the outcomes and not the myriad of perceived necessary procedures does help speed up gameplay. However the engagement of sparring partners is also something worth considering in IGOUGO systems. If the non-active player has a reason to be engaged on their opponent’s turn it’s not a bad thing. Though it’s rather redundant in solo play of course!

    • Yes, I agree that interaction of the non-active player is a good thing. Saving throws do that for sure, but personally I’m not keen on saving throws because they slow the game. But different folk will have a different preference.

      And different games will keep the non-active player involved in different ways.

  3. If I understand it right, both spotting and morale test do something only if target is in cover. That means unit in the open is hit on 4+ (3 hits on average with 6d6), while unit in cover gets a saving roll, where the value of save depends on result of spotting. That would be 1.166 hits if I am not mistaken.

    Your alternatives on the other hand completely eliminate any advantage of cover, unless I missed something. I agree that spotting roll is kind of unnecessary here. Morale here is simply cover save, which could be incorporated into firepower roll by introducing some modifier to spare dice (for example 4+ to hit in the open, 5+ in cover).

    But I have to agree that abstraction is generally key to better and more fun games.

    • Petr, the entire thread was about targets in cover; I even mention that. As I said, there are lots of other rules I don’t consider and making this change in isolation would break lots of things.

  4. Interesting post. I do this as well, bit only for games I think I am going to play a few times. I even try to get it down to either a few d6 or a single d6 roll with a few modifiers.

  5. Have you or anyone in your group found a battalion level game that works for you? Blitzkrieg Commander, Command Decision, etc?


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