Game: B
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Hollow Earth Expedition

First Edition

A popular "pulp" rules system, designed for a non-Indiana Jones world

Publisher Description

First we discovered that the Earth is round.

Then we discovered that it’s hollow.


An RPG Specifically Designed for Pulp Adventures [ edit ]

Hollow Earth Edition ("HEX") is an RPG with a setting ... and that setting isn't the world of Indiana Jones.  However, it is a very similar world: it's set in 1936, and adventures revolve around the characters searching for ancient secrets ... only instead of looking for lost artifacts, they're exploring a mysterious "hollow world" inside our planet.  One reviewer even compared HEX to the 1992 computer game Indiana Jones and the Fate of Atlantis, where Indie similarly goes in search of a lost realm.

But even if you don't want to use its setting, the "Ubiquity" rules system used by HEX is specifically designed for "pulp adventures", which makes it extremely easy to adopt to any other pulp setting ... including the world of Indiana Jones.

Hollow Earth Expedition, First Edition - Rules SummaryCollapse

Character Creation [ edit ]


To create a HEX character you first select an "archetype", such as Adventurer, Celebrity, Occultist or Reporter.  Archetypes are similar to classes, but have far less in-game impact; the rules suggest that you "think of
them as concepts and stereotypes for you to build upon,
not as templates of skills and abilities."


Next, the player selects their character's driving goal. Every character must choose one, because it takes a strong motivation for a person to adventure all the way inside the Earth itself, and the GM can reward characters for role-playing their motivation with "style points".  Motivations are limited by archetype, so for instance an Adventurer, Celebrity or Reporter might have Fame as a motivation, but not any other archetype.


Next the player spends 15 points (on a one-for-one basis) to purchase their six primary attributes.  Every attribute has a minimum of one point and a maximum of five.  These attributes are almost identical to those in Dungeons and Dragons, except that Constitution and Wisdom have been replaced with Body and Willpower.

After the primary attributes are determined a number of secondary/derived attributes are calculated based on the primary attributes.  These include the character's size, move, initiative, and stun/health.


Next the player selects from among 30 skills for their character (eg. Animal Handling, Investigation, Melee, or Stealth).  Skills aren't limited by archetype, although the game encourages you to pick skills that match, and each character gets 15 points to spend (max 5 in any one skill).

Skill Specializations

Characters can also "specialize" in a skill by spending half a skill point.  For instance if a character wanted to better with shotguns than other firearms they could spend half a point to specialize their firearms skill.  Characters can only have one specialization in each skill (at creation), and it gives them an extra die when the specialization is applicable to the roll.

Talents and Resources

Each character gets either a single Talent (unique ability) or Resource (connections/wealth).  Talents include things like being charismatic, being able to fight blind, being extra-large, or simply being lucky, while resources include things like artefacts the character has collected, mentors or followers, or just plain old wealth.

Some talents and all resources can be purchased multiple times to increase their effect: for instance, a single level of wealth provides a $250/month stipend, while a second level instead provides $500/month, and a third level increases the amount to $1000/month.


Each character may optionally choose to start with a Flaw.  Whenever that flaw negatively impacts the character they earn a style point as a result (and also start the game with an extra point).  Flaws include being absent-minded, disfigured, mute, or unlucky.

Starting Experience Points

Somewhat unusually for an RPG, HEX gives characters 15 experience points to spend at character creation.  The character can spend these points to improve their attributes/skills/specializations, or they can spend all 15 to purchase a single extra talent or resource.

Core Mechanics [ edit ]

Hollow Earth Edition has a somewhat unique system: as a "d2" system every die roll is essentially just a coin flip: an even result indicates a success, while an odd result indicates failure.

Action Types

To perform an action the player first determines the type: standard, extended (ie. a long-term action, like repairing a vehicle), opposed (an action that another character is trying to stop) or reflexive (an opposed action made in response to another's action).


Next, the GM then sets the target number, from 1 (for an easy task) to 6 (for a nigh impossible one), and the player rolls their dice pool trying to achieve that many successes.  Their dice pool is equal to their relevant attribute plus relevant skill, plus modifiers for other factors (eg. a bonus if they are using a good set of tools, or a penalty for trying to make the check in the dark)

Taking the Average

To save unnecessary rolls and keep the game moving, if the character's dice pool is greater than or equal to twice the target number (eg. 4+ dice for a TN of 2) .... or in other words, if the character would succeed on an average roll ... the character succeeds automatically.

Degrees of  Success and Failure

Whether the character succeeds or fails, the amount that they succeeded/failed by is used to determine how well/poorly the action failed.  This is particularly relevant in combat, as additional successes on the roll result in increased damage.

If a roll doesn't have a single success (ie. even number) that roll is considered a critical failure, and the GM determines an appropriately negative result for the character.

Style Points

Characters can earn style points through good role-playing, particularly with their Motivation and/or Flaw(s).  These points can then be spent to purchase extra dice for critical rolls (as well as for other benefits, such as a temporary increase to a talent' level or to reduce damage taken).

Chance Dice

If a character is feeling lucky they can opt to get two bonus dice ... at the cost of adding one to the TN (statistically the two balance out on average, so this essentially just introduces extra randomness to the roll, adding to the game's pulpy feel).  A player can get up to ten dice this way, but they cannot "take the average" if they do.

Combat [ edit ]


Each character has an initiative score (derived from their Dexterity + Intelligence), which they roll to determine their initiative order.  This roll is repeated every turn (six seconds) of combat, and higher initiative rollers can hold their action to wait and go later.


Each turn a character can take a single attack, defense, and move action.  Attacks and movement are performed on the character's turn, while defenses are reflexive actions (when attacked).  Characters can also Sprint or take a Total Attack or Total Defense action to forego an action type in exchange for a bonus to the main action.

There also a variety of actions for specific types of combat actions, ranging from aiming, to charging, to attacking cautiously, to tripping .


To attack the GM first determines modifiers for the target's size, range, visibility, and wound penalties, and then the attacker makes a roll using the appropriate melee or ranged attack skill (eg. firearms).  The defender then makes an opposed defense roll, and if the attacker beats the defender's roll they hit (ties go to the defender).


Each weapon has a fixed Damage Rating, and deals either lethal or non-lethal damage.  For example,  a punch has a DR of 0 non-lethal, while a gatling gun deals 4 lethal damage.  For every extra success on the attack, the attacker adds one to their weapon's damage.


Each character has a Health score (their body + willpower + size) which is essentially their hit points: when reduced below zero the character falls unconscious, and at -5 Health they die.

Damage can also have other effects.  If a single hit's damage exceeds the character's Stun (ie. body) score they lose a turn, and if they take more than double that score they are instead knocked out.  Similarly if an attack's damage exceeds a character's Strength score they are knocked back or (if it exceeds 2x Strength) knocked down.

Hollow World Expedition vs. Savage Worlds [ edit ]

Both HEX and Savage Worlds are great modern systems for running any sort of "pulp" campaign (not just Indiana Jones, but other similar settings like the world of The Mummy).  You can't go wrong with either one for your Indiana Jones campaign, so it simply comes down to a matter of preference.

Savage Worlds is the "heavier" system of the two, and also the more versatile: while HEX is specifically designed just for pulp campaigns, Savage Worlds rules can be used for anything from Medieval fantasy, to the wacky worlds of Dreadlands or Rifts.  With more detailed rules, including more character creation options and campaign/setting-specific rules, Savage Worlds allows you to create and nearly anything you could want using it.

In contrast, HEX focuses just on pulp settings, and its rules are much quicker and faster (and arguably are just a bit more "pulpy").  While neither system will give you a pre-built "world of Indiana Jones" to use, the pulpy "hollow earth" world of HEX, gives a good starting place, and many campaigns may simply want to use that setting as is (if they want an "Indiana Jones" feel, and don't mind exploring a new world, instead of hunting ancient artifacts).

In short, pick Savage Worlds if you want a great generic RPG, with solid and fairly detailed rules, that can support almost any campaign (and can do a pulp one particularly well).  Pick Hollow Earth Expedition if you want a fast, extremely "pulpy" system ... or if you want to explore the hollow earth yourself.

Free Quickstart Rules/Adventure [ edit ]

To get a "quick start" version of the HEX rules, you can download a free adventure/quick start rules that they released for Free RPG Game Day 2011.  You can no longer download that adventure from the publisher's site (see the warning below), but it is still available here (thanks RPG Academy for hosting it!)

One Version, Two Printings [ edit ]

To play Hollow Earth Expedition you can choose from two different printings of its core rulebook.  The first printing is a hardback, while the second is a softcover, but there are reportedly few (if any) differences between them.

There is also a digital version of the Hollow Earth Expedition, available through Drive Thru RPG.  However, there are numerous reports in the comments for it about poor formatting of the PDF, so until a new PDF is released, with better formatting, we recommend sticking to the print books unless you need a digital copy.

Warning: A Finished Game

One thing to be aware of however: Exile Games (the publisher of HEX) is no longer in business, and its creator has reportedly moved on to another company (to work on Savage Worlds material).  As a result, no new HEX content is expected to be released, although there are other new games being made using its core d2 Ubiquity rules (namely the "Leagues of ..." games from Triple Ace Games).

However, the game itself can still be enjoyed,  as you can find both its core rules and many supplements (both official and unofficial) on stores like Amazon, EBay or Noble Knight.  Also many of those supplements are still available on Drive Thru RPG from Black Campbell Entertainment (they are often branded as being "for Ubiquity", but their descriptive text makes it clear they're primarily designed for HEX).