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Osiris Core Rulebook (v 1.3)
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Osiris Core Rulebook (v 1.3)

Suggested Price $8.99

Welcome to Epidemic Osiris, the open-source RPG system that offers the perfect blend of realism and game speed.

The Epidemic Open-Source Roleplaying System (OSRS), or as we call it, Osiris, is a general framework of rules for running any sort of Role Playing Game.  The open-source part means that you are free to add to it, run your games in it, and publish supplements and adventures using Osiris as the ruleset.

Osiris is not a setting in and of itself, but simply a rule system for adjudicating role-playing.  It flows fast-enough for storytelling, but is crunchy enough for the most serious gamers to sink their teeth into.  It is designed for creative types who want a string, realistic framework to run their games in.  We don't write your stories for you (that part's up to you, though we have some examples on our website), we just deliver a solid set of game mechanics to make your stories come to life.

There’s no need for you to have played or understood any other role-paying game (or even know what an RPG is) in order to make full use of Osiris.  The Osiris introductory chapter is designed to help you understand how to use this book and how to get the most out of your role-playing sessions.  More experienced readers may feel free to jump ahead to Chapter 1 and start learning the basic rules, but you may want to go back and read the introduction anyway–running a great game is not just about knowing the rules.

Osiris is not geared towards a particular game setting or style of play, but is general enough to work in almost any situation. It has performed brilliantly in campaigns ranging from space-opera to high-fantasy, and modern horror to buccaneers and high seas. This entirely new set of rules is designed to be faster than other systems, add more realistic mechanics, and offer greater flexibility.  Anyone familiar with other RPGs should be able to pick Osiris up relatively quickly, and new players should be able to learn it rapidly as well.

The key elements of Osiris are as follows:

  • Simpler, faster, yet far more realistic combat mechanics.
  • No character classes – you can be exactly who you want to be and do what you want to do.
  • Separate Wound and Stamina stats to add more realism and more surprises to your combats.
  • A greatly improved magic system – spells are not random effects, but learned skills that build upon each other to combine and expand into greater powers (sold separately).
  • Characters are no longer limited by their starting stats – natural gifts will be a great boon for new characters, but experience and skill will always win the day.

This deluxe 1.3 version of the Osiris core rules includes a full battalion of all-color art, an introductory chapter to role-playing, plus 10 additional vignettes designed to inspire your imagination, and a final chapter on running a game session by Todd Morasch.

1.3 is our second "ready for prime-time" edition, meaning we are satisfied that this edition is a fully-fledged original that covers all the situations that may come your way.  However, we are always updating it as new topics arise.  If you buy any edition of this ebook, we will always upgrade you for free as we release new editions.

So jump right in and start reading.  We guarantee with Osiris you will spend far less time thinking about the rules and far more time crafting epic tales together.

Note: This is the ebook edition.  If you are looking for a printed copy of the beautiful, full-color, 234-page hardcover Osiris book, head over to the Epidemic Books website.

Osiris is a living work and is constantly improving with use and feedback.  This expanded 1.3 version contains the following changes from the previous 1.2 version:

  • Field skill trained rolls are cheaper (1 for 1d12, 1d4 for 2d8, 2d4 for 1d20, 3d4 for 1d30)
  • Improved cheat sheet
  • More serious falling damage
  • Increased alt strength bonus for ranged weapons
  • Improved fire rules (basically incorporating the enhanced rules from the book of fire)
  • Numerous new heroic powers
  • Better prerequisites for the heroic powers (focus switched for awareness where it makes sense)
  • Slight cost and power tweaks to the heroic powers
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Customer avatar
Christopher F October 04, 2013 9:21 pm UTC
Wonderful description of what you want the rule system to be, and absolutely nothing about what the game is about...
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56.07 MB
Original electronic
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These products were created by scanning an original printed edition. Most older books are in scanned image format because original digital layout files never existed or were no longer available from the publisher.

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File Last Updated:
July 14, 2017
This title was added to our catalog on October 04, 2013.