Revisiting Opposed Tasks in Hack100

My one nagging doubt about Hack100’s rules, which refuses to go away, is the “highest roll wins” tie-breaker for Opposed Tasks.

Opposed Tasks arise when a character pits one of their Abilities against a counter Ability of another. For example, Stealth vs Perception. Or melee combat.

At the highest level, the outcome of an Opposed Task is determined by the overall “quality” of the two opposing rolls. A Critical beats an ordinary success, which beats an ordinary failure, which beats a Fumble. However, two opponents will often achieve the same overall result. For example, both might achieve an ordinary success, or both might Fumble. In such instances, a secondary means of determining the outcome is needed.

In the current version of the Hack100 rules, the Opposed Task tie-breaker is “highest roll wins“. This has the advantage of being simple. It also favours the more proficient competitor, which seems reasonable.

However, “highest roll wins” also has a couple of drawbacks. Firstly, in combat, one of the contributions to the Damage arising from a successful attack is the “tens” die from the Task Roll. Therefore, the higher the Task Roll, the higher the Damage. With “highest roll wins” this means that if both combatants’ Melee Task Rolls are unsuccessful, but the attacker’s roll is higher (perhaps 90%+), then they are going to inflict very high Damage upon their opponent even though they rolled poorly. Indeed, potentially considerably more damage than if their Task Roll had been successful. This could be thought of as a “lucky wild swing”, but it doesn’t feel quite right to me.

Secondly, “highest roll wins” essentially breaks the core mechanic of percentile-based systems, which generally follow a “low rolls are good” principle.

Therefore, I have taken a look at some alternative approaches to tie-breaking Opposed Tasks in Hack100 to see if I can find a more satisfactory option.

Alternative Tie-Breakers for Opposed Tasks

We will consider three options for Opposed Task tie-breakers, specifically in relation to melee combat:

  1. Highest roll wins (the current approach).
  2. Lowest roll wins.
  3. Highest roll wins if both Task Rolls are successful (i.e. Criticals or ordinary successes); lowest roll wins if both Task Rolls are unsuccessful (i.e. Fumbles or ordinary failures).

To evaluate these options, I went back to the combat simulator described in a previous blog. This is a simple script in which I’ve coded the Hack100 combat system for two melee opponents slugging it out against one another.

The first set of charts below is for two opposing combatants with uniform Abilities (i.e. all their Abilities have the same percentage value and their Health is derived accordingly). Each is armed with a +4 Damage Modifier weapon (e.g. a one-handed sword) and both are unarmoured. The charts show the percentage of battles each would be expected to win for various Ability match-ups. Green represents a 50% win rate (i.e. an even fight), yellow represents a 75% win rate for one of the combatants, and red represents a 100% win rate. The colours are graduated between these fixed points.

Highest Roll Wins

It can be seen that for “highest roll wins” the non-red band is very narrow. If one opponent has only a 10% Ability advantage, their likelihood of winning is in the 70-80% range. At a 20% Ability advantage, the win rate rises to over 90%.

Lowest Roll Wins

For “lowest roll wins“, the non-red band is noticeably wider. The increase in win rate with an increasing Ability differential is much less dramatic.

Highest Roll Wins if Both Successful, Lowest if Both are Unsuccessful

The third option – “highest roll wins if both are successful, lowest if both are unsuccessful” – sits somewhere in the middle.

The next chart examines a different aspect. Here the two combatants have the same constant Abilities (50%) and the effect of differences in the Damage Modifiers due to their weapons and/or armour is examined. We see a quite different trend, with “lowest roll wins” being the most sensitive to equipment Damage Modifiers.

Effect of Damage Modifier on Combat Outcome

Interpreting the Findings

Overall, what we are observing here is that the different tie-break options place a different emphasis on the two components of the Damage arising from a successful melee attack: (i) the component due to the “tens” die of the winning Task Roll and, (ii) the component due to the Damage Modifier(s) arising from a combatant’s weapons and armour.

Highest roll wins” places a much stronger emphasis on the “tens” die component. Winning Task Rolls will generally be higher, which means that their associated Damage is also higher. Combats tend to be short and dangerous. The Melee Ability of a combatant is generally more important than their weapons and armour.

With “lowest roll wins“, winning Task Rolls are generally lower and this means that the Damage component arising from equipment becomes proportionally more significant. The lower overall damage output also means that fights will last longer in comparison to “highest roll wins“.

Highest roll wins if both are successful, lowest if both are unsuccessful” sits somewhere in between. It may provide a better balancing of the relative importance of Melee Ability and equipment when it comes to determining the outcome of a fight.

We can also get a good sense of these findings if we repeat one of the examples from another earlier blog in which we pitted a more skilful fighter against one that is better equipped. The set-up was:

One fighter with Abilities of 60% and a one-handed sword (+4 Damage Modifier) … 

against …

another fighter with Abilities of only 40% but wearing plate armour (-3 Damage Modifier) and carrying a two-handed sword (+6 Damage Modifier). 

With this scenario, the combat simulator predicts the following, quite different, outcomes:

  • Highest roll wins” leads to a 76% win rate for the more skillful fighter.
  • Lowest roll wins” has a 61% win rate for the better-equipped fighter.
  • Highest roll wins if both are successful, lowest if both are unsuccessful” has it 57% / 43% in favour of the more skilful fighter.

Of these three outcomes, I’m most comfortable with the third option. It seems to strike the best balance. When a combatant makes a successful Opposed Melee Task Roll, it rewards higher proficiencies by increasing the potential damage output from the tens die. For situations in which both combatants are unsuccessful, it reduces the likelihood of extreme damage.


In the next release of the Hack100 rules I’ll be swapping out the “highest roll wins” tie-breaker for Opposed Tasks and replacing it with “highest roll wins if both are successful, lowest if both are unsuccessful“. It’s a marginally more complex approach but seems inherently fairer. 

Nevertheless, by all means stick with the existing “highest roll wins” if you prefer shorter combats that emphasise character skill. Or use “lowest roll wins” if you’d like an equally simple approach that places a higher emphasis on equipment. Hopefully, this blog has highlighted some of the implications of choosing one tie-breaker over another.

7 replies on “Revisiting Opposed Tasks in Hack100”

Hi, I really like what you’ve achieved with a simplified d100 system. But as far as opposed rolls go, my suggestion would be go with lowest roll wins – which as you point out is quick and intuitive – and change the damage calculation thus: subtract the lower winning tens digit from the losers tens digit. That’s your damage, plus weapon bonuses etc. So now you have factored in relative skill results, with the additional wrinkle that the losers roll still counts – a loss by a small margin equals less damage, by a great margin a lot more damage.

Hi Greg – thanks for the feedback. It’s a good suggestion and one that I’ll have a look into. I think the major implication will be an overall reduction in Damage levels. If we adopt the lowest roll wins principle, then a successful roll of 40 vs a successful roll of 50 (for example) would give a Damage contribution of 4 under the existing Hack100 system, but only 1 under your proposal. This might lead to quite long, attritional combats. But I’ll run your suggestion through the analysis described in this blog and see what the differences are in practice.

Hi again Greg – I ran your suggestion through the combat simulator and, within the limitations and assumptions of that artificial environment, the results were very similar to a straightforward “lowest roll wins” tiebreaker. The average fight length was slightly longer, but typically only by a single round. And the fight outcome data (i.e. who won) was very close to that reported for “lowest roll wins” in the original blog above.

So, I’ll probably leave things as they are. The logic of your suggestion is sound, but mechanically it seems to make negligible difference compared to simply using “lowest roll wins”. The additional complexity doesn’t change the outcome (at least according to the scenarios tested in the simulator).

Hi Joe,

In Hack100, can the 20% or 10% bonus to an Ability at character creation instead be applied to a beginning character’s starting Specialism?

That way, say, a medical doctor character is guaranteed to be the best in medicine, even when another beginning character rolls exceptionally well in their Reasoning Ability score.

Rules as written, a beginning character who rolls two tens on an Ability score and then adds their 20% bonus gets a 60% starting score, whereas starting Specialisms top off at 50% (unless the 10% or 20% bonus at character creation can also be applied).

What are your thoughts?

Thank you Joe,

Brian C.
Chelmsford, Massachusetts

Hi Brian,

Strictly speaking, rules as written, no. But I think that would be fine as a house rule.

Also, bear in mind that, I wouldn’t equate a”Medical” Specialism with a general “Reasoning” Ability when it comes to something like first aid. Even if the scores were same, when performing first aid I’d either apply an appropriate Difficulty Modifier (easier for the specialist, harder for the generalist) or allow the specialist a better potential outcome (e.g. 1-5 Health healed for the Specialist, just 1 point for the generalist).



OK – thanks Joe! And please excuse any cross-posting of my question…I posted it on Twitter/Drive-ThruRPG/direct email…any place I thought you might check 🙄😬

Leave a Reply

Your email address will not be published. Required fields are marked *