These guys should never win!

These guys should never win!

Today I’ve been thinking about ways to remodel Warhammer Fantasy Roleplay 2 (WFRP 2) to make it more user friendly and less punishing, and in the process of thinking through the system’s underlying probabilities I have run up against a problem with the reference frame for skill tests that I think is common for many systems. The problem is a simple one that afflicts opposed skill checks: depending on who is considered to be the active initiator of the skill check, the same skill check can give different probabilities of an outcome. This situation is particularly stark in WFRP 2, though I think it might afflict other systems too. Here is a brief explanation of the problem and how it can (and can’t be) solved. I wonder if this problem is part of the reason that people get so frustrated with the WFRP 2 system and always feel like they’re failing …

The WFRP 2 opposed skill system

WFRP 2 uses a stat-based skill system to resolve skill checks. Stats range from 0 to 100 and an unopposed skill check is resolved by rolling d100 and trying to get under your stat. So e.g. if your agility is 40 then you will succeed in a basic agility check 40% of the time. There are modifications of course (skill training, etc.) but this is the basic process. For an opposed skill check, each person involved in the skill check makes their roll, the person initiating the check starting and then their target rolling under the opposing skill. For example in combat the attacker rolls for Weapon Skill and then the defender rolls their Weapon Skill or Agility in order to parry or dodge. In an opposed skill check your chance of success is always lower than your base stat: it is stat * (1 – opposing stat). This creates a punishing probability curve, incidentally: a person with a stat of 50 up against a target with a stat of 50 has only a 25% chance of success, and perversely this is the best in the game. If you have stat 90 and you are up against someone with stat 90 your chance of success is 9%. But this is only part of the reason that WFRP 2 punishes players.

How reference frame affects outcome

Consider the following example. Bob the Hapless needs to sneak into a tavern to steal one last drink, so he first needs to get past the guard at the door. He has Agility 40 and the guard has Intelligence 40, so it’s an opposed skill check, Bob’s 40 vs. the guard’s 40. Bob rolls, the guard rolls, and fortunately Bob rolls a 01 and the guard a 41, so Bob gets through. His chance of success here was 40*60=24%, not so great; this means, note, that the guard’s chance of spotting him was 76%.

Now Bob the Hapless is near the bar, but he doesn’t realize that a skaven assassin is in the room, and is sneaking up on him. So now Bob the Hapless needs to do an observation check to notice the skaven assassin if he wants to avoid being ambushed. The assassin has a stealth of 40 and Bob has an intelligence of 40, so they roll. Now Bob’s chance of success is 40*60=24%; this means that the skaven had a 76% chance of sneaking up on him.

Unsurprisingly, Bob’s chance of continually beating 24% odds is not good, and he fails the second roll – he rolls a 39 but the skaven rolls a 7. Bob is ambushed and, as one might expect, soon becomes ratfood. This is because he got rat-fucked by the system. When he had to make a stealth check with agility 40 vs. intelligence 40, he had a 25% chance of success; but when the skaven had to make a stealth check with agility 40 vs. intelligence 40, it had a 76% chance of success. For the same check!

Why this happens

In WFRP 2 there is an initiator and a defender of any opposed skill check. The initiator needs a specific chain of outcomes: her own success and her opponent’s failure. But the defender doesn’t need a specific chain of outcomes: they only need either a failure or a success. Essentially once the initiator fails the defender doesn’t need to roll, but if the initiator succeeds the defender gets a second chance to dodge the outcome. Success for the initiator is a conditional probability (on the defender failing); whereas success for the defender is a marginal probability of either the defender succeeding or the initiator failing.

This might not be a problem except that GMs tend to try to make the player the active participant in a skill challenge: if the player is stalking, then the player makes a stealth check against which the GM defends; if the player is being stalked the player makes an observation check against which the GM defends. But this desire to make the player the active participant of their own adventure massively reduces their chance of success; and until they reach a stat of about 50 this effect is punishing – and becomes punishing again after stat 50!

Does this happen in other systems?

I think this doesn’t happen in systems with dice roll vs. DC systems, because usually if the skills/stats are balanced then they cancel each other out and only the probability distribution of a single die roll matters. Shadowrun has an opposed skill check system where each player rolls a dice pool, but in this case the outcome is determined slightly differently: the defender’s roll sets a target that the initiator has to beat, effectively ensuring that if the initiator rolls well above a threshold they’re likely to win (see below for how this can affect WFRP2). I remember playing Talislanta or Aria (not sure which) and finding the same problem, that you could never hit anyone in combat, and I think it had the same underlying mechanic. I think this mechanic is used in quite a few systems, though I haven’t played them all obviously. I don’t think WFRP 3 has it because the difficulty of skill checks is set by the opponent’s attribute and this is asymmetric: in the above example everyone would have the same dice pools in all situations.

I think this problem is merely particularly noticeable in WFRP 2 because all the PCs start off so terrible that you really feel the problem.

How to fix this problem

There are a couple of simple solutions to this problem. The first and most obvious is to design a better system. A partial solution would be to require the defending character to roll under the number obtained by the initiating character and under their own skill. So in the above example, when Bob rolled 01 for his stealth check there was no way the guard could see him; but when he rolled a 39 on the second check there was a big chance that the skaven could roll under his result (which it did). This only partially fixes the problem, since if the player rolls near their stat, the number the defender needs is effectively only constrained by the upper bound of their own attribute. It also doesn’t work when one player’s attribute is much lower than another’s. I think Dark Heresy (the Warhammer 40,000 game) has a modified version of the mechanic that uses a version of this system based on degrees of success that may partly solve the problem.

The best solution is to define active and passive skills, so that for example Observation is always a defender skill and stealth always an attacker skill. This solution has two problems though: attacker skills (like hitting people and sneaking past people) will always be much, much harder than defender skills, which will encourage people to develop characters and gameplay styles based around not doing these things; but more importantly, RPGs should put players at the heart of the action so that wherever possible they initiate skills rather than defending against them. Setting up a system of skills where some are always initiated and some are always defended will mean that some players will be very good at what they do, but will never be put in the active position in doing what they do. I think this doesn’t match the ethos of gaming that most players enjoy.

Basically, skill tests should always be resolved by a single, simple dice roll that is in the hands of the player as much as possible.

Can WFRP 2 be fixed?

I just completed a follow-up session to the Slaves of Destiny adventure I did a while back, again using WFRP 3. It was a lot of fun but this time around we had a large gang of skaven slavers to fight (report to come) and it was just impossible for me to properly follow the rules – or even anything like them – when GMing all those monsters. I didn’t even have table space for the cards! I like the system but in the absence of thoroughly stripping it down and making it much simpler, it’s a good way for PCs to operate but a terrible system for the GM. I would like to be able to use the WFRP 2 rules, because all the surrounding material is great and the game has such a strong feeling, but I just hate them. However, I think with a few tweaks to the central mechanic [well, a complete change] the stat blocks, career system and everything else could be retained in their entirety, and the game become an enjoyable and frustration-free romp through a really great world. In many ways WFRP 2 is an almost perfect combination of world-setting, atmosphere, writing, art and game system: except its fundamental mechanic is broken. I think that mechanic can be fixed by dividing all attributes by 10 and employing a 2d6, Traveler-like mechanic. I will come back to this soon I hope, to describe how to do it – and maybe also test it with some of my players.

If I could find a way to enjoy playing WFRP 2 I would be a very, very happy GM …