Ondath
Hero
Please note that this is a [+] thread. If you think it is impossible to represent D&D 5E's flavour within the OSE framework, you're entitled to your opinion. However, what I really want to do here is to discuss how such a representation could be done with people who think it's possible.
I've been running 5E for almost 8 years now, and I've had some experience running OSE, though not as much as I'd like. I feel like I'm starting to grok the fundamental math behind the game, as well as the game style OSE tries to push you towards. I especially like how the concept of "genre books" allows you to use the same game chassis to play very different games (of course, you have to stick to the fundamental philosophy of the OSR, but that should still allow a wide range of genres and ideas). We couldn't see the full potential of this idea since the post-apocalypse genrebook never materialised, but I really like how the Advanced genrebook means that a B/X Dwarf can play at the same table as a Drow Acrobat.
And you know who else has promised this kind of modularity? That's right, D&D Next! We never got the promised modular system that would allow an AD&D-style Illusionist to play at the same table as a 4e-style Warlord, and I think that's a shame. However, if OSE can allow B/X and AD&D characters to play together, maybe it can also allow 5e-style characters to join the fray...
So this is my proposal: A Neo-Fantasy Genre Book for OSE. I've been mulling over the idea for a while now but didn't have time to work on it seriously, but I've got a couple of months with a lighter workload so I really want to hammer the fundamentals of this project when I've got the time. What I'd really like from the lovely ENWorld community is to provide feedback on some of my ideas, and perhaps brainstorm with me a bit on some questions that I couldn't entirely resolve.
Parts that I think are resolved: I think these aspects of the system can be adapted without much issue, or I have some idea how to do it that I'm happy with:
Level Progression & Hit Dice
This might come as a surprise, especially since classes advancing at different paces is one thing that separates old school D&D from modern D&D. But here's the thing: When you look at it, all classes advance using the same table (XP), it's just that some classes (namely, the Magic-User) have a lot of dead levels. If everyone's progression was charted following M-U XP tables, we could something like this:
With this progression, everyone levels up at the same time, but the practical power level of, say, a Level 16 Neo-Fantasy Fighter is the same as a Level 18 OSE Fighter. Funnily enough, when non-Wizard classes get their level progression squished like this, their hit points end up following a curve closer to what they'd get with 3E-like hit dice (assuming you stop rolling dice at level 9, which I always liked as a rule): A level 23 OSE Thief would have 49 HP on average with 9d4+28 hit dice, and if you spread that to a 20-level progression, you get... 9d6+22, which rounds out to 54 HP, pretty close! Similarly, a Neo-Fighter's Hit Die can become d10, Cleric's d8, but Magic-User stays at d4. All in all, I think it's possible to have a parallel level progression for every class that maintains the Old-School balance style.
Skills
I think it's easy to implement a rudimentary version of 5E's skill proficiencies in OSE that follows the "roll 1d20+ability modifier vs DC" unified mechanic. However, it's important to keep such a system as barebones as possible to avoid players seeking answers on their character sheet. I won't elaborate on it now, but I think it's one of the easier problems to solve. I think even the Thief's percentile skills can be rolled into this system in a way that largely preserves the probabilities of success.
Encounter Balance
I know this is practically blasphemy for the OSR, but I actually think the rules for balancing encounters on pages 100-101 of the Rules Cyclopedia are basically sufficient to replicate something like the Challenge Rating system. It gives you the sufficient tools to see whether your encounters are balanced for the party based on their composition and the enemies' Hit Dice. You could even extrapolate some monster math out of these guidelines, add 5E's "65% accuracy against level-appropriate targets" and "3-round combat" expectations when designing monster ACs and so on... Overall, I think OSE can replicate this kind of combat balance surprisingly well.
Parts that are somewhat resolved: With these, I've got the beginnings of an idea, but some things still bother me.
"Proficiency bonus" as a unified modifier
One of the things that makes 5E simplistic is the fact that your proficiency bonus is applied to everything you're good at: Your attack rolls, spell save DC, skill checks, saves... This number is the same for everyone at the same level. In 5E, a level 9 Wizard knows their spell attacks get a +4 bonus from proficiency, while a level 9 Fighter adds the same +4 bonus to their attacks. The THAC0 bonus is a pretty good contender for this. Especially since bonuses to saving throws also tend to follow a similar progression (plus or minus 1 point). However, the THAC0 progression varies wildly across classes at the same level, so it might be a bit difficult to grok for new-school players (what do you mean the Neo-Fighter gets a +7 to their saves at Level 12, while the Magic User gets a +5?).
Levels 14+
You might have noticed that I reference levels 14+ in my levelling table. But that brings the question: Since B/X (meaning also OSE) ends at Level 14, how do we decide what comes after? I think more heroic higher levels are a staple of modern D&D (leaving aside the question of how often people get there), and a Neo-Fantasy genre book should include them. However, I don't think we can copy the rules straight from BECMI, since they retroactively nerf the Thief and fiddle with save progressions to spread everything up to 36 levels. Personally, I think 36 is a big much. Level 20 seems like a more natural limit in the modern playstyle, so that's why I thought the XP progression should end at the equivalent of a Level 20 Magic User. For Levels 15-20, I intend to use the excellent B/X Companion as an inspiration (mixed with AD&D-style limits for the THAC0/save progression), as I think the numeric progression and the new spell options are all in B/X's spirit, but also capture high-level D&D quite well. Levels 15-20 could be the Companion tier, compared to the Basic tier of Levels 1-3 and the Expert tier of levels 4-14.
Parts where I still have no idea what to do: At first glance, the way OSE and the way 5E does these things feels way too different to reconcile easily. I'd love people's ideas on how to deal with them.
Spell levels
I have to say, this is a mess in OSE, especially when Advanced classes and spells are included. At 600000 XP (11th level in our unified progression), the Magic User can cast up to 6th level spells, which include things like Anti-Magic shell, Control Weather, Projected Image and Reincarnation. At the same XP threshold, the Cleric only has spells up to 5th level, and what those can do vary incredibly from their supposed namesakes. This gets worse when you consider OSE Advanced classes: The Druid is stuck at 4th level spells, but their 4th level spell list includes Transmute Rock to Mud, which is a 5th-level spell for the Magic User. What's more, the Druid started using that spell at 20000 XP (Level 5), while the Magic User had to wait until 300000 XP (Level 9)! What's worse, the Illusionist has the same spell slot progression as the Magic User, but while Projected Image is a 6th level spell for the MU, it's a 5th level spell for them! However, the MU gets to cast Dispel Magic as a 3rd level spell, while it's a 4th-level spell for the illusionist... Do you see why I'm getting a headache? This is a convoluted, incomprehensible mess compared to 5E where all full caster progress at the same pace in terms of spell slots, and all classes get equivalent spells at the same spell levels. I don't know where to begin to get these two paradigms agree with each other, especially if I want to maintain compatability with OSE Classic/Advanced Fantasy rules...
Character Customisability
In OSE, classes are simplistic. It's one of the big selling points: You get all the info you need about your class in a 2-page A5 spread. It makes referencing a breeze. But I don't know how this can play together with the kind of choices 5E is supposed to present to you at each level: You're supposed to be able to choose a subclass, fighting styles, feats... And I want to replicate the range of playstyles covered by these choices, without codifying all of a character's capabilities in the character sheet. I think Chromatic Dungeons is a pretty nice approximation, but even that is a bit barebones. This I think is one of the things 5E-inspired retroclones tend to miss: I like stuff like 5 Torches Deep, but they simplify the options so much that I feel like I lose some of the depth that I enjoy in 5E. I don't know how this could be replicated. Perhaps trying to simplify the rules complexity of different choices, but not their numbers would be a place to start. Make it so a Druid can choose between different circles, but their abilities aren't expressed as "You can do X action Y/Long Rest", but more in terms of the game world's fiction. Even this would very quickly destroy the 2-page spread limit, but perhaps this can be changed so that each class has a 2-page spread for each Tier: The Wizard has 2 pages for levels 1-3, 2 pages for levels 4-14 (where you also choose a subclass), and 2 pages for levels 15-20. I feel that something like this could possibly work, but it'd be a tough job to start "translating" 5E choices/features to the Old School style.
If you have any ideas about how to approach this crazy project, I'd love to hear it!
I've been running 5E for almost 8 years now, and I've had some experience running OSE, though not as much as I'd like. I feel like I'm starting to grok the fundamental math behind the game, as well as the game style OSE tries to push you towards. I especially like how the concept of "genre books" allows you to use the same game chassis to play very different games (of course, you have to stick to the fundamental philosophy of the OSR, but that should still allow a wide range of genres and ideas). We couldn't see the full potential of this idea since the post-apocalypse genrebook never materialised, but I really like how the Advanced genrebook means that a B/X Dwarf can play at the same table as a Drow Acrobat.
And you know who else has promised this kind of modularity? That's right, D&D Next! We never got the promised modular system that would allow an AD&D-style Illusionist to play at the same table as a 4e-style Warlord, and I think that's a shame. However, if OSE can allow B/X and AD&D characters to play together, maybe it can also allow 5e-style characters to join the fray...
So this is my proposal: A Neo-Fantasy Genre Book for OSE. I've been mulling over the idea for a while now but didn't have time to work on it seriously, but I've got a couple of months with a lighter workload so I really want to hammer the fundamentals of this project when I've got the time. What I'd really like from the lovely ENWorld community is to provide feedback on some of my ideas, and perhaps brainstorm with me a bit on some questions that I couldn't entirely resolve.
Parts that I think are resolved: I think these aspects of the system can be adapted without much issue, or I have some idea how to do it that I'm happy with:
Level Progression & Hit Dice
This might come as a surprise, especially since classes advancing at different paces is one thing that separates old school D&D from modern D&D. But here's the thing: When you look at it, all classes advance using the same table (XP), it's just that some classes (namely, the Magic-User) have a lot of dead levels. If everyone's progression was charted following M-U XP tables, we could something like this:
| Magic User/Unified Level (XP) | Equivalent OSE Fighter Level | Equivalent OSE Thief Level | Equivalent OSE Cleric Level |
| 1 (0 XP) | 1 | 1 | 1 |
| 2 (2500 XP) | 2 | 3 | 2 |
| 3 (5000 XP) | 3 | 4 | 3 |
| 4 (10000 XP) | 4 | 5 | 4 |
| 5 (20000 XP) | 5 | 6 | 5 |
| 6 (40000 XP) | 6 | 7 | 6 |
| 7 (80000 XP) | 7 | 8 | 7 |
| 8 (150000 XP) | 8 | 8 | 8 |
| 9 (300000 XP) | 9 | 10 | 10 |
| 10 (450000 XP) | 10 | 11 | 11 |
| 11 (600000 XP) | 12 | 12 | 13 |
| 12 (750000 XP) | 13 | 13 | 14 |
| 13 (900000 XP) | 14 | 15 | 16 |
| 14 (1050000 XP) | 15 | 16 | 17 |
| 15 (1200000 XP) | 17 | 18 | 19 |
| 16 (1350000 XP) | 18 | 18 | 20 |
| 17 (1500000 XP) | 19 | 20 | 22 |
| 18 (1650000 XP) | 20 | 21 | 23 |
| 19 (1800000 XP) | 22 | 22 | 25 |
| 20 (1950000 XP) | 23 | 23 | 26 |
Skills
I think it's easy to implement a rudimentary version of 5E's skill proficiencies in OSE that follows the "roll 1d20+ability modifier vs DC" unified mechanic. However, it's important to keep such a system as barebones as possible to avoid players seeking answers on their character sheet. I won't elaborate on it now, but I think it's one of the easier problems to solve. I think even the Thief's percentile skills can be rolled into this system in a way that largely preserves the probabilities of success.
Encounter Balance
I know this is practically blasphemy for the OSR, but I actually think the rules for balancing encounters on pages 100-101 of the Rules Cyclopedia are basically sufficient to replicate something like the Challenge Rating system. It gives you the sufficient tools to see whether your encounters are balanced for the party based on their composition and the enemies' Hit Dice. You could even extrapolate some monster math out of these guidelines, add 5E's "65% accuracy against level-appropriate targets" and "3-round combat" expectations when designing monster ACs and so on... Overall, I think OSE can replicate this kind of combat balance surprisingly well.
Parts that are somewhat resolved: With these, I've got the beginnings of an idea, but some things still bother me.
"Proficiency bonus" as a unified modifier
One of the things that makes 5E simplistic is the fact that your proficiency bonus is applied to everything you're good at: Your attack rolls, spell save DC, skill checks, saves... This number is the same for everyone at the same level. In 5E, a level 9 Wizard knows their spell attacks get a +4 bonus from proficiency, while a level 9 Fighter adds the same +4 bonus to their attacks. The THAC0 bonus is a pretty good contender for this. Especially since bonuses to saving throws also tend to follow a similar progression (plus or minus 1 point). However, the THAC0 progression varies wildly across classes at the same level, so it might be a bit difficult to grok for new-school players (what do you mean the Neo-Fighter gets a +7 to their saves at Level 12, while the Magic User gets a +5?).
Levels 14+
You might have noticed that I reference levels 14+ in my levelling table. But that brings the question: Since B/X (meaning also OSE) ends at Level 14, how do we decide what comes after? I think more heroic higher levels are a staple of modern D&D (leaving aside the question of how often people get there), and a Neo-Fantasy genre book should include them. However, I don't think we can copy the rules straight from BECMI, since they retroactively nerf the Thief and fiddle with save progressions to spread everything up to 36 levels. Personally, I think 36 is a big much. Level 20 seems like a more natural limit in the modern playstyle, so that's why I thought the XP progression should end at the equivalent of a Level 20 Magic User. For Levels 15-20, I intend to use the excellent B/X Companion as an inspiration (mixed with AD&D-style limits for the THAC0/save progression), as I think the numeric progression and the new spell options are all in B/X's spirit, but also capture high-level D&D quite well. Levels 15-20 could be the Companion tier, compared to the Basic tier of Levels 1-3 and the Expert tier of levels 4-14.
Parts where I still have no idea what to do: At first glance, the way OSE and the way 5E does these things feels way too different to reconcile easily. I'd love people's ideas on how to deal with them.
Spell levels
I have to say, this is a mess in OSE, especially when Advanced classes and spells are included. At 600000 XP (11th level in our unified progression), the Magic User can cast up to 6th level spells, which include things like Anti-Magic shell, Control Weather, Projected Image and Reincarnation. At the same XP threshold, the Cleric only has spells up to 5th level, and what those can do vary incredibly from their supposed namesakes. This gets worse when you consider OSE Advanced classes: The Druid is stuck at 4th level spells, but their 4th level spell list includes Transmute Rock to Mud, which is a 5th-level spell for the Magic User. What's more, the Druid started using that spell at 20000 XP (Level 5), while the Magic User had to wait until 300000 XP (Level 9)! What's worse, the Illusionist has the same spell slot progression as the Magic User, but while Projected Image is a 6th level spell for the MU, it's a 5th level spell for them! However, the MU gets to cast Dispel Magic as a 3rd level spell, while it's a 4th-level spell for the illusionist... Do you see why I'm getting a headache? This is a convoluted, incomprehensible mess compared to 5E where all full caster progress at the same pace in terms of spell slots, and all classes get equivalent spells at the same spell levels. I don't know where to begin to get these two paradigms agree with each other, especially if I want to maintain compatability with OSE Classic/Advanced Fantasy rules...
Character Customisability
In OSE, classes are simplistic. It's one of the big selling points: You get all the info you need about your class in a 2-page A5 spread. It makes referencing a breeze. But I don't know how this can play together with the kind of choices 5E is supposed to present to you at each level: You're supposed to be able to choose a subclass, fighting styles, feats... And I want to replicate the range of playstyles covered by these choices, without codifying all of a character's capabilities in the character sheet. I think Chromatic Dungeons is a pretty nice approximation, but even that is a bit barebones. This I think is one of the things 5E-inspired retroclones tend to miss: I like stuff like 5 Torches Deep, but they simplify the options so much that I feel like I lose some of the depth that I enjoy in 5E. I don't know how this could be replicated. Perhaps trying to simplify the rules complexity of different choices, but not their numbers would be a place to start. Make it so a Druid can choose between different circles, but their abilities aren't expressed as "You can do X action Y/Long Rest", but more in terms of the game world's fiction. Even this would very quickly destroy the 2-page spread limit, but perhaps this can be changed so that each class has a 2-page spread for each Tier: The Wizard has 2 pages for levels 1-3, 2 pages for levels 4-14 (where you also choose a subclass), and 2 pages for levels 15-20. I feel that something like this could possibly work, but it'd be a tough job to start "translating" 5E choices/features to the Old School style.
If you have any ideas about how to approach this crazy project, I'd love to hear it!
