Under the Hood – Baseline Physics


Baseline Physics
By The Warden

466081471_727128059b_b-940x626For the next paragraph, I need you to imagine it spoken in the words of the immortal voiceover master, Don LaFontaine. If you don’t exactly know who that is, it’ll make sense once you start reading.

In a world where the laws of reality play by no one’s rules, where right and wrong are more than constructs of the system, one man struggles to overcome the oppression of the machines. Where not even gravity plays fair and danger is all in your mind. One man must fight against the machines to save humanity and the woman he loves.

See? Much cooler with the LaFontaine voice in your head.

If the purpose of roleplaying games is to escape from the ordinary and everyday restrictions of reality, we have found ways to not only leave reality behind, but to turn it on its head and break what is considered the foundations of physics. How does the hyperdrive work in Edge of the Empire? Doesn’t matter, it just does and the Millenium Falcon remains the fastest hunk of junk in the galaxy. Teleporting from one location to another with a wave of a wand and some strange, nonexistent words? Done and done, so long as you don’t fail your Spellcraft roll and wind up stuck halfway inside a stone wall or knee deep in larvae from the Nine Hells.

Who needs reality when we can make up whatever we want and have worlds, galaxies, and societies bound to these new, imaginative, and hypothetical principles? When the game is well underway and players are right in the thick of the moment, suspension of disbelief is at full swing and everyone simply accepts these principles to be true because it fits within the system and tone of the game. Fitting those exceptions to the laws of physics and making them work as part of the game provides that suspension of disbelief and without a proper fit into the game’s mechanics, things can get horribly out of shape real fast.

Let me give you an example and let’s assume you’re playing a Hitchhiker’s Guide to the Galaxy RPG. You’re about to press the big red button to activate the improbability drive and hope you’ll be able to reach your destination intact and with little morphing into yarn as possible… but every time you use it, things work perfectly without issues. For plot purposes, this is salvation in any other game, but if you’re trying to play the Hitchhiker’s RPG as if you were in the original novels, it’s no good and your suspension of disbelief is gone. Because the setting has established the function of the improbability drive and its complete randomness of events, a new law of physics has been established: the laws of reality can be bent for comedic effect. By failing to hold up to the standards of your game’s new laws, you have broken the crucial suspension of disbelief and failed to achieve the goal of playing in a true Hitchhiker’s RPG.

This same principle applies to original material as well, regardless of genre, history, locations, or what have you. When I first picked up the Planescape boxed set back in the day, it provided a very concrete and scientifically impossible principle of multiple infinite dimensions accessed by a series of two-dimensional portals no more difficult to pass through than a door with the proper key. Within each Outer Plane, a new list of principles applied to meet the tone and style of the plane, forcing players to adapt to the subjective gravity and howling winds of Pandemonium or the stacked infinity of the Abyss with deeper and deeper layers of pure chaotic evil. If you travelled to the peaks of Mount Celestia and reached the top within a couple of days, something’s not right. The impact of ascending the rocky cliffs housing the realms of gods is instantly diminished into nothing more than a fancy story made up by drunken peasants. Bad news, your game just became silly.

Establishing a game’s understanding of the world and how it interacts with itself and living creatures is something I like to call “baseline physics.” In the same way our world has a specific amount of gravity, environment, the circle of life, and everything else we take for granted, a game must establish its baseline physics and accompany those baselines with appropriate rules or else the game loses its believability faster than the apple falling onto Newton’s head. Even games taking place in the “real world” have to conform to what we know and expect from reality unless there are specific reasons to gloss over certain laws and standards.

The reason why I use “baseline” in the term baseline physics is because mechanics are not expected to mimic every nuance of physics in their components. If anything, it’s preferred they tone things down a bit. A modern military RPG heavily involved in automatic weapons could take the time to discern how to mathematically simulate the effect of a small 3-round burst versus firing a single controlled shot, but if you create a burst mechanic forcing the players to complicate their action, you risk losing the players’ interest in the game (or their willingness to fire a 3-round burst, at least). So we shortcut. Rather than work off the same foundation of physics from our reality, game designers translate it into shorthand by establishing task resolutions. Determining the path of a bullet fired from a real gun involves math that would occupy an entire university-sized blackboard; in a game, it’s represented by rolling a d20, adding a modifier, and comparing it to your opponent’s defence number. From there, you can determine that burst provides a small increase to your odds of success and add a d6 to your attack roll, or you take a -2 penalty when firing a burst in exchange for double damage if you hit.


New worlds and unique settings designed to stretch the imagination have a choice in how their baseline physics will affect the game: work from a general assumption and simply allow these baselines to happen automatically or provide them as a bonus/difficulty in the game. These choices can create a fundamental difference in gameplay and must be carefully considered for the final version. If anything, you may need to adapt and tweak over time until you have the right balance for what your game needs.

For example, during some playtests for a recent Wild West/wushu game I was running, I wanted to establish a baseline of realistic gravity with the exception of unique individuals (the major characters in the setting, including villains and goons) who can jump higher than your average person and otherwise defy the standards of the gravity we all know and love. The later drafts provided these characters with an exception to the standard rule and allowed them to automatically ignore any increased difficulty based on the baseline that an ordinary person functions the same in this game as they would in real life. If an ordinary person wanted to balance themselves on a delicate tree branch, they would have to attempt it against a very difficult target number and risk falling to certain death; a heroic character, on the other hand, could ignore that difficulty and simply attempt it as if it were a normal task.

This was not always the case. In the original drafts of the game, heroic characters gained bonuses to their physical abilities to represent their exception to this baseline and it quickly got out of hand. Since heroic characters were never pitting themselves against ordinary people as a general rule, everyone rolling dice was adding on these bonuses and pretty much cancelling them out. If everyone in your game is adding +5 to their rolls, no one’s actually gaining that bonus. Eliminating the bonus from heroic characters and placing the burden on the common, unpowerful no-names made more sense and required less work.

Finally, you have to consider if your game’s baseline physics are too much to allow players infinite access, a consideration typical for converting existing systems to new worlds and new baseline physics. Providing access to flying in d20 systems, for example, can be incredibly overpowering unless it’s available to everyone. Limited access can massively tilt the scales in a flying character’s favour and so many flying abilities are limited to spells and predetermined durations or a structured number of times per day. Different types of vision are another deal breaker. If you’re creating a dungeon crawl game and toss out the impact of darkness by allowing every player to have darkvision, do you risk diminishing the impact of hiding in shadows and subterfuge in your game?

A better example is the introduction of the warforged race to D&D mythology and its original setting, Eberron. Providing a mechanical race of people not only fit to the setting’s advanced applications of magic and technology, it practically screamed it at players. Denying us the warforged race would have gone against everything exciting about the setting, but it comes with a few surprisingly advantageous benefits, not the least of which involves the lack of sleep or breathing.

Unfortunately, simply playing as a typical construct in the d20 System meant one massive exception: no Constitution score. Removing it from this PC race meant screwing around with hit points and other essential factors to game play and success, so an exception had to be made for the baseline physics of Eberron to work with the game’s mechanics. Warforged were living constructs with Constitution scores and specific immunities, strengths, and limitations (healing damage, for one thing) balancing out this race with other, more traditional living creatures.


Setting your baseline physics can be as easy as basic assumptions or complex options and it’s not something your game should take lightly. Because we’re starting to run out of time for this week, we’ll take a look at some of the standard baselines for many RPGs. Deal?

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