Impetus and Basic Impetus

After a long hiatus, I finally have for you a review of Impetus by Lorenzo Sartori of Dadi & Piombo.  Impetus is a game of massed combat using large and chunky elements.  The author aims to provide a simple but fun game of Ancient combat while also providing a good looking table top of miniatures.

The Book

Impetus comes as a spiral bound book printed in full color on heavy stock paper.  The book is 50 pages long and has numerous photos for inspiration and diagrams that help to illustrate how the game is played.  There are army lists at the end of the book and there is a points system published online.  There are also several supplement book which provide more army lists as well as campaigns and historical backgrounds.


In general two armies broken up into a number of commands is required to play Impetus.  This will usually be 100 + figures when using 15mm figures in the suggested base sizes.  I used DBA stands to represent units and use the smallest scales (1U=1cm).  The game played fine.

Before the battle can commence, the players will go through the setup routine to set out terrain.  This is a very simple but effective process.  Players will each throw 2 dice.  High roller is the attacker.  The defender will place 2-4 pieces of terrain.  The attacker will then have the option to move or remove 1 piece of terrain.  There is a chance for a built up area (village) and a river.  The defender will throw 1 die for each.  If a 5+ comes up, that terrain piece is also available in the mix.  Like I said, simple but effective.

The Rules

Impetus has an unusual turn order.  As stated before, each army is broken into a number of commands, usually 2-4.  Each command has a general with a leadership modifier based on how effective the general is.  Each player nominates a commander to move, rolls 2 dice and compares the results.  The high roller must move.  The player moves, shoots and melees with all units in that command.  Once he is done, both players nominate another command to move.  Once all commands have moved, a new turn begins in the same fashion.


A player nominates a unit or group of units to move.  The units may move straight ahead or wheel.  They may do both but risk disordering the unit or group.  The first move or wheel is ‘free’.  Each subsequent move or wheel the player rolls a die and compares to the discipline number for the unit.  If it is less than that number, the unit is disordered and may not move again.  Each move increases the chance of failure by 1.  Commanders can influence the discipline roll if they are part of the unit or group making the roll.

There are some reaction moves that can be done if a unit enters the zone of control (5U in front of the inactive players unit).  For instance, if a unit makes a move not directly at the enemy unit, the enemy could take a shoot of opportunity.   As well, a unit could be placed on opportunity and be allowed to interrupt the enemy with an opportunity charge or a shot of opportunity.

When charged, light cavalry and skirmish infantry may evade away from the charger 1 move.  Pretty standard stuff.


All combat in Impetus and Basic Impetus is done using the same game mechanic.  Each unit is rated with a ‘Basic Unit Value’ or ‘VBU’.  This number will range from as low as 2 to as many as 8.  The higher the number the better.  To this are added tactical and support bonuses for other units and situations as well as the impetus value (I) if the unit is charging and is fresh (has not taken any hits).  An attack invloves rolling dice equal to the modified VBU.  For each ‘6’ or pair of ‘5s’ rolled, one hit is registered.   The player owning the target unit must now roll a cohesion test.  The number is the target units VBU minus the number of hits received.  A ‘1’ always passes and a ‘6’ a;ways fails.  If the die roll is greater than the target number, the difference is the amount of permanent damage the target unit receives.   The target unit VBU is reduced by this amount.  Both sides of a melee get to fight before damage is recorded.  The unit that takes the most permanent damage is the loser of the combat.  It retreats a variable amount.  The attacker may pursue a variable amount.  If the attacking unit catches the target unit, another melee immediately begins.

Missile combat is a little different.  As well as tactical modifiers, there is a bonus or penalty for the type of weapon used depending on the range to the target.  There is a vast array of missile weapons rated in the game.  Missile combat is not simultaneous.  The attacker only causes damage to the target.

Regardless of combat, when a unit takes hits, whether it passes a cohesion test or not, that unit is disordered.  If it was already disordered and passes a cohesion test, it take 1 point of permanent damage. Damage from accumulated disorder is not considered when determining the victor of a melee.

Large units are an interesting aspect of Impetus.  Warbands and Hoplites can usually form two units deep and Phalangites (Pikes) can form four units deep.  The effect of these large formations is to give the front unit extra dice for each additional rank.  The back unit takes damage based on the cohesion of the front unit and is eliminated first.  The whole unit is not worn until the front unit actually takes damage.  If a large unit is flanked and subsequently fails a cohesion check, the whole unit routes.

Winning and Losing

The game is over when one side has reached its breakpoint in ‘Demoralization Value’ or ‘VD’.  Each unit in an army has a VD.  One half the sum total of the VD is the break point for the army.  As untis are eliminated, the VD of that unit is deducted from the total VD for that army.  When the total VD is zero, the army breaks.  Individual commands can break as well.   The VD has to be calculated for each command.  When one command breaks, all of those units count as breaks for the whole army.  So, it is possible for an army to break before an individual command breaks.  It is also possible that 1 command breaking will break the whole army.

Under the Hood

On the surface, the game is pretty simple.  You roll dice, count the hits and apply them to a cohesion test.  There are also some things that alter the game so that it becomes fairly chaotic.  For instance, when you roll for initiative, you must move the command you chose whether you want to or not.  You might win all of the initiatives for the turn leaving your opponent with the opportunity to move his commands in any sequence he chooses.  Depending on how well you moved during your turn, this may leave you with a long and horrifying wait as your opponent picks your army apart.

Dispirit combat values are not as bad as they seem.  With a little luck, a VBU 2 unit can possibly win a melee with a VBU 6 unit.  I wrote a probability calculator using Troll Roller.  The average hits for VBU 2-6 are as follows:

VBU 2 Hits .36,  VBU 3 Hits .57,  VBU 4 Hits .79,  VBU 5 Hits 1.03,  VBU 6 Hits 1.27

It would not be too unusual to see a VBU 6 unit miss and see a VBU 4 unit score at least 1 hit.

Another aspect of the game is the higher attention to detail paid to the missile combat system.  There are several long bows, composite bows, self bows, a sling, a javelin, 2 crossbows and 3 types of artillery.  Considering that the melee combat system contains little in the way of weapon detail, I found this a bit surprising.  I would have thought that 1 bow and a long/composite bow category would be enough for bow.  The differences in types is usually 1 die and often only at certain ranges.  Simplifying the list of missile weapons would not change things up that much and would fall in line with the simplicity of the melee combat weapons.

I felt the reaction system did not really add much to the game.  It seemed a bit complicated and fiddly for what it was trying to accomplish.  The games played fine without it.  I think I actually used it once.  As the movement rules are pretty restrictive, I don’t even think special ZOC rules are required.  I would be simpler to allow a counter charge by a unit that is in good order and it passes a discipline test.  Similarly, I think it would be OK for a missile unit to shoot if it was charged by an enemy, but only if it were in good order and it passed a discipline test.

Roman line relief was the one historical rule that I had a problem with in the game.  The rules require that you make 2 cohesion tests, one for each unit trying to interchange.  With that, there is a fairly low probability of actually performing the maneuver.  Long handing 2 average units trying to swap spaces would be 50% X 50% or a 25% chance to actually perform the maneuver.  Seems low for something that was a main feature in the Roman army’s success during the time of the Republic.  I would just allow it to happen if the back unit is in good order and the front unit is not engaged or is retreating from a lost melee.

Finally, I’d like to talk a moment about the organization and editing of the rules.  Some folks felt that the rules were hard to understand.  After reading through, I could see why.  The rules set is a translation from Italian.  The wording, while correct through out, could seem a bit awkward and occasionally hard to understand.  With two English language proof readers, the quality of the translation should have been better.  The organization of the book could have also been better.  For the most part, it flowed relatively well.   However, with regard to zones of control and reaction/opportunity, the rules were spread out to several sections.  There were several other minor instances of rules that I had trouble finding.  The book could have done with an index to alleviate the problems.

I played 3 games of Impetus with 2 commands per side.  My first game was Greeks vs Persians at Marathon.  For this battle, no rules changes were needed.  The Persians fought two units deep with the archers in the rear and mixed units in the front.  They were able to inflict some loses on the advancing Athenians but for the most part, the game held up to history.  The armored hoplites closed and made short work of the Persian infantry before the cavalry could join the fight.

The second game pitted a Pyhrric army vs the might of Rome.  This one went down to the wire.  The consular army advanced to contact and started a shoving match with the more numerous and deeper deployed pikes.  At first the Romans were getting the worst of it but started to grind down the pikes and were only just broken with a charge from the rear by the Pyrrhic Agema cavalry and the elephants.

The third fight was Carthage vs Rome.  It was similar to Zama but I simply made 2 armies and added a few Numidians to Rome.  The Carthaginians lined up in three lines and kept the cavalry on the flanks.  Romans were in two lines.   Both armies used skirmishers to the front.  The battle started with the Romans besting the first punic line after a brief struggle.  The carthaginian Numidians bested the Roman Numidians but the Roman cavalry locked in a struggle with the Punic cavalry which lasted most of the game.  After blending through the second punic line, the Punic veterans of the third line proved too much for the worn Romans.  The fight was over.

In all three fights, no rules modifications were needed.  They played well.  I especially liked the way that the large units could be ground down by a superior unit after the initial contact.  The accumulated disorder rule was great at representing this.  Units would get disordered but stay stuck in, thus not being able to rally/reform.  Missile fire could seem a little powerful.  Some weaker units that take a hit could leave the field if they rolled a 6 for cohesion.  Occasionally, the cohesion rolls could get a bit dicey.  On one occasion, I rolled four 6’s for hits and then rolled a 1 for the cohesion test.  No effect.  I liken this to the old Squad Leader morale check.  You roll very low and get a morale check +4 on the enemy. Then the enemy rolls 2 for the test and barely passes.  The number of hit are not casualties but rather the psychological effect on that unit of losses during combat.

I played several games of Basic Impetus as well.  It is, indeed, a ‘lite’ version of the full game.  The games were over in under an hour.  They did have the feel of the era in a basic way.  I played my last game of Basic Impetus with a few rules from Impetus, including my modified reaction rules and the evade rules for skirmishers.  It gave a fun little game with a relatively low figure and unit count.

The support of the game from Dadi & Piombo is quite good.  There is a forum on the website as well as a Yahoo Group.  The author is active at both sites answering questions about the game.


The game plays well and is a nice and (mostly) uncomplicated treatment of Ancient warfare.   Once I got rolling, I enjoyed the game a lot.  Despite the difficulties, I think that the full version of Impetus is worth the money. The game comes in two versions.  The first is Basic Impetus.  It is free from the authors website and includes a large amount of army lists.  It will give you a good idea of how the combat system works.  It’s free so you have nothing to lose.  The second version is that which is reviewed here.  The cost is about $42 in the US and can be ordered from your favorite hobby retailer.

Basic Impetus


Both by Lorenzo Sartori and published by Dadi & Piombo

Price $42

20 Responses to Impetus and Basic Impetus

  1. Bobm says:

    An interesting read. I enjoy Impetus a lot and play it regularly. The varying missile weapon categories are essential to differentiate troops who were mainly shooters from those for whom melee was preferred, they aren’t so much representing different weapons as a tactical modifier in most circumstances as units use the same basic factor for their close and distance combat.

  2. Dan Beattie says:

    A model review. I especially liked that you actually played the rules before evaluating them in print.

  3. Excellent review, as always. I do like the fact the rules are packed with useful diagrams. I must get around to playing more than one game someday.

    Regarding Basic Impetus: It is a good fun ruleset in its own right, but like you, could not help but put just a couple of extra rules in.

  4. Gaius Cassius says:

    I don’t agree that the Missile Fire Table needs modification. Some of the bow classifications have two or even three grades. The reason for this is simple. Take Composite Bow as an example. Composite Bow A represents footbow armed with composite bow. Composite Bow B represents mounted troops whose primary weapons is bow. Composite Bow C represents mounted troops who were armed with composite bow but rely primarily on shock and melee to achieve results. There are two grades of Short Bow. Short Bow A represents foot units armed with bow and Short Bow B represents skirmish units armed with bow. Of course, there are some exceptions to the above. Poor troops might have a lower designation. But overall the Missile Fire Chart is graded to make it very simple to look up results.

  5. acarhj says:

    Hi all,

    My point about the missile chart is that 90% of the game has low detail and gradations. Then we have the missile chart that has more than a dozen options to choose from. The game, being not that detail oriented when it comes to equipment really does not need this sort of detail in the missile weapons, especially when many of the weapons vary by less than a die. The extra weapons just don’t add much to the game. The variations by type are quite low.

    I plan to post some heretical mods in the near future including a simplified missile chart.


  6. Excellent review!

    I just wanted to mention that the Roman line relief rules have been modified in Extra Impetus 4 which was just recently released. I don’t have my copy yet but from what I understand they are much better now.

  7. Gaius Cassius says:

    The answer to your question John, is yes, the current Missile Table is needed to simplify the missile fire. So for instance, there is a huge difference between Composite Bow A and B. The difference is primarily found at long range where Composite Bow A can do real hurt to mounted units whereas, Composite Bow B is really only effective at Short or Point Blank range. And this seems realistic to me.

    Having played 50+ games let me assure you that the Missile Chart is not overly complex and the basic numbers are rather easily remembered.

  8. Gaius Cassius says:

    Further thinking John, you obviously don’t understand the subtlies of Impetus. So before you go making a simplified missile fire chart how about playing 30 to 40 games with different armies. Then, if you feel a need to make up the chart, go ahead.

  9. acarhj says:

    Indeed I do understand the subtleties of the game. Composite bow A is very similar to Longbow A. What’s in a name? Why not make then the same stats? Composite bow B is very very similar to Short bow A. Make them the same stats. You simplify by calling them Longbow/Composite bow and short bow simply bow. Now, troops using the longbow or composite bow on foot should use the former which equates to Long Bow A. Any troop using short bows or are mounted and use a bow should use the Bow which equates to Short Bow A. Needless variations for bows alone. The list could be reduced down to 6 kinds of missile weapons and 3 kinds of artillery (I did not change that) and nobody would even notice the difference in play. “More” is not necessarily “better”.

  10. I am with John on the missile fire table. There are lots of subtleties in the table, but compared to the rest of the game it stands out as extra detail that is missing in other sections – why not more detail on other weapons for example – long pikes vs shorter ones, axes, two handed weapons, shield variance (large, medium, small,no shields). If the argument is that this is captured in VBU and some special rules, then why not have a simpler missile table that captures the effect as well? It isn’t that the missile table does not provide a great level of differentiation, it is that this level of differentiation is out of sync with the rest of the rules, that does not. I have no issues that the missile table providing a great level of detail and have no problems playing with it. But I would have preferred a simpler table, as that would align with the rest of the rules.

  11. PilGrim says:

    Hi Gents
    First, thanks for the review, I found it well balanced on the whole. If I could comment on the missile chart for a moment, I do think those suggesting amendments and simplification are missing the point. I suppose if what you want is a much blander game you could just say you have fewer missile types, but on the whole the system works well. The difference in missile weapons is more critical than melee weapons because the VBU stat has dual purpose in the game mechanic in that it judges melee effectiveness and unit durability. If you had fewer missile weapon options you would find some units with missile and melee capability would be overpowered, a example would be good quality cavalry such as Mamlukes. It also makes quite a difference to skirmishers, which are a whole micro game in themselves. I’m also a bit puzzled as to why you would want to, unless you prefer blandness?
    The layout is a little clunky, and there are some translation issues, but on the whole I have to admit I’m a fan.

  12. PilGrim says:

    Hi John. I should add that after a couple of years playing I’m not sure I fully understand “the subtleties of the game” so I look forward to your amendments with some interest.

  13. acarhj says:

    Hi all,

    To say that fewer missile weapons is “bland” is to say that the melee combat system is “bland”. There are, as Shaun (above) points out, very few melee weapons defined. 2 I think. Sure you can do stuff like over-sized units but you can fire from rear ranks with missile fire.

    Finally, I’d like to say that my mods I will post in the next day or so are what I will use in my games. I am not suggesting that the game must be changed or it is somehow broken. It is your game so play it how you like. Horses for courses…or so I’ve heard. ;-D


  14. Gaius Cassius says:

    You can of course make any mods you like John. But I do find it a bit galling that after playing only a few games you feel sufficiently educated in Impetus to make any changes at all. I’ve been playing Impetus for 3 years stead now (a couple of times a month) and am still figuring out the subtlies of the game. What makes you think that you know better than the rules designer and the many people who play with the game?

    How about playing 30 to 40 games with different armies first? Doesn’t it make sense to become fully acquainted with the game first before embarking down a new path?

  15. acarhj says:

    Wow. I’m not sure why the hostility. It’s just a game. I mean seriously.

  16. PilGrim says:

    Sorry John, no hostility intended on my part at least, but I think to be honest there is a valid point in that suggesting you understand the subtleties after 3 games is quite a claim. After my third game I thought warband were invincible, now they’re seen as such a liability that they appear very rarely in competitions. By game 5 I was convinced light horse was god, til I learned by experience otherwise. After two years regular play I still don’t really “get” the interaction of skirmishers with other units, so regularly get my arse handed to me both in club play and competition by opponents who do. Impetus has a fascinating learning curve, and after 3 games I don’t believe you or anyone is really very far up it.

    The “blandness” of melee again seems to be you missing the point – ie half dozen or more different weapon combinations \ fighting styles are represented – shieldwall, schiltron, long spear, pike , pilum, warband, line relief, etc before you take into account the interactions between troop types. It’s much more subtle and nuanced than it looks at first, and the melee rules are as detailed \ comprehensive as those for missile fire, indeed I would say more so. It’s just those differences are represented in different parts of the rules mechanics.

    Obviously you can post and play what you like, the Rules Orthodoxy Police don’t operate in this part of the world, but it seems a shame to start making changes when you have not really seen the full picture, as much for your own good as anything.


  17. acarhj says:

    I don’t actually think melee is bland. I also don’t think that cutting out the unnecessary detail from missile combat will make that bland either. Finally, the whole point of playing 3-4 games before a review is to pick up the subtleties and interactions in a game system. If I were to write a review like this and not have played a game of Impetus, then I’d be flat out wrong.

    I guess we should agree to disagree at this point.


  18. Very comprehensive. Thank you.

  19. Steve Holmes says:

    Nice review, has convinced me from 60% to 95% to buy the rules

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