Remaking 2d20 for Achtung! Cthulhu
By Nathan Dowdell
First appearing in 2013 with Mutant Chronicles 3rd edition, the 2d20 System has been a part of the way Modiphius makes RPGs for nearly as long as Achtung! Cthulhu has existed, so it feels inevitable that, eventually, the two would be put together.
This change wasn’t made lightly, nor was it done without a good deal of consideration as to how the 2d20 System would need to be altered to suit the specific needs of our blend of occult/cosmic horror with pulp action-adventure. 2d20 is a system that has always been reconstructed in various ways to serve different settings and styles of play, and the varied games that use the system are a testament to that: while the core mechanics remain the same, you’ll get a very different play experience with Conan: Adventures in an Age Undreamed Of than you will from Star Trek Adventures or Dishonored.
So, here’s a few insights into how we’ve adapted the 2d20 System to serve the needs of Achtung! Cthulhu.
Pulp Adventure vs Occult Horror
The two central tones of Achtung! Cthulhu are, as noted above, pulp action-adventure stories within the Second World War and Occult or Cosmic Horror. The two genres have never been entirely separate, as demonstrated by the cosmic horror elements that appear in Conan stories, but how you mix them has a big impact on the result.
Previously, this was handled by using two different game systems for the mechanical side of things. Call of Cthulhu allowed players to lean more into the horror aspects, while Savage Worlds emphasised the other side of things, with larger-than-life heroes and their action-packed adventures.
This new edition, using the 2d20 System, leans more towards the latter than the former, with the supernatural and cosmic horror aspects meant to be threats to overcome (even if only briefly) rather than terrors that cannot be truly confronted, and with extra emphasis on the fantastical superscience and mystical powers of the villains… and that of the heroes.
The core of the 2d20 System remains the same familiar system you all know: roll two (or more) 20-sided dice, trying to get equal to or under a Target Number set by your Attributes and Skills to score successes, extra successes become Momentum, and the GM has a pool of Threat to serve as “evil” Momentum for the villains.
Achtung! Cthulhu goes back to a more traditional style in a few places. A longer skill list—twelve skills, mixed-and-matched freely with six attributes—than the brevity of Star Trek Adventures or Dishonored, and the attributes list is a familiar set of Agility, Brawn, Coordination, Insight, Reason, and Will.
Along with this, the game makes considerable use of Truths, seen elsewhere in Dishonored and named Traits in Star Trek Adventures to cover a lot of the varied situations, effects, and nuanced details of the world. Truths are single words or short phrases that describe a fact about the world, and which give those facts a bit of mechanical impact by affecting the difficulty of skill tests, allowing some tests to be attempted, or preventing others from being possible. A common form of Truth in the game is an Injury, which could either be physical (from blades, bullets, and other physical threats) or mental (representing fear, panic, mental strain, and the effects of facing otherworldly horrors). These injuries can, in some circumstances, lead to permanent changes to your character in the form of Scars, which represent the long-lasting effects of the most serious injuries, and serve as a natural way to evoke the sanity-eroding nature of Elder Gods and their minions.
The combat rules should be familiar to players of Infinity, Conan, and Star Trek Adventures, though refined further to try and take the best elements from each and keep play from bogging down too much while still allowing player characters to take a range of different approaches to action scenes. Alongside combat, we’ve introduced a revised form of the Extended Task mechanics from Star Trek Adventures to add some depth to some non-combat tasks, though the mechanic has been significantly cleaned up from its earlier incarnation and draws a lot from the tracks mechanic seen in Dishonored.
One of the reasons for Extended Tasks is magic. The structure of an Extended Task, with multiple actions contributing to a larger, risky, activity, is an ideal fit for performing the kinds of bizarre rituals, whether being attempted by Nazi Black Sun cultists, or by Player Character occultists. Meanwhile, smaller spells intended for the battlefield use a simpler system inspired by the supernatural powers seen in Mutant Chronicles and the magic system in Conan.
There were numerous other small changes, too, such as an improved set of vehicle rules given how important vehicles can be to the World War II setting (and to some characters, who may be expert drivers or mechanics), but this post would go on forever if I detailed every single tweak and adjustment made to the system. My advice? Have fun exploring them all for yourself.