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5th Edition Ruleset


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A while back, I acquired copies of the 5th Edition rulebooks and immediately wondered how much of the system could be translated into the Infinity Engine. I've been passively experimenting with various implementations of features from 5th Edition, and I've been pleasantly surprised by how much of the system can be approximated (if not fully implemented) within the Enhanced Infinity Engine.


A brief overview of the important mechanics is provided below:





Advantage and Disadvantage

One of the biggest systems in 5th Edition is the concept of advantage and disadvantage. For those unfamiliar, whenever you make a check that has factors in your favor (granting "advantage"), you roll two dice and take the higher number; conversely, if you make a check in unfavorable conditions (imposing "disadvantage"), you roll two dice and take the lower number. If you have both advantage and disadvantage, they cancel each other out and you simply roll a single die. After this, you add whatever numerical modifiers you may have to the roll, and that produces the final result.


As the engine does not (and likely will never) support this "roll 2 dice, take higher/lower" functionality, I instead looked at probability and examined the average increase or decrease that advantage or disadvantage caused. Advantage, on average, is about the same as adding +3.2 to your roll, and disadvantage is about the same as applying a -3.2 penalty to your roll.


Within the context of this mod, I have made advantage count as a non-stacking +4 bonus to a given d20 roll, and disadvantage counts as a non-stacking -4 penalty on the given d20 roll. As rogue skills function on a percentile basis, advantage and disadvantage give a +20% or -20% bonus, respectively.


(From an internal mechanics standpoint, all player controlled characters, summoned monsters, and enemy NPCs that can see a player character have an effect that applies appropriate advantage/disadvantage bonuses once per second.)


Resistance, Vulnerability, and Immunity

Much like its approach to situational modifiers to checks, 5th Edition also simplified how damage type resistances behaved. For each damage type, a character can either be immune (meaning they don't take any damage), resistant (half-damage), vulnerable (double damage), or none of the above (normal damage). Immunity negates vulnerability, and resistance and vulnerability cancel each other out.


Bounded Accuracy

Another significant change that 5th Edition uses is that there is a much tighter restriction on numerical bonuses to rolls. Characters may add an amount to rolls on which they are "proficient" that typically varies between +2 and +6, plus whatever the appropriate ability modifier is (which is capped at +5 except in certain circumstances). Thus, a fighter with 16 Strength at 1st level has an attack bonus of +5, while a 20th level fighter with 20 Strength has a +11 bonus, for a total change of +6 across 20 levels of experience. Conversely, in 2nd Edition, a 1st level fighter with 16 Strength has a +0 bonus to hit, while a 20th level fighter with 20 strength has a +22 bonus to the same roll (and this is before you count magic items and specialization bonuses and a host of other benefits.)


This allows content that is not exactly at the characters' level to not be annoyingly trivial or impossibly difficult, and offers a decent amount of consistency with difficulty checks (e.g. a DC 20 roll is nearly impossible for someone untrained, but a max level character trained in that will still only succeed about 50% of the time).


Reduced Magic

Tying into bounded accuracy, 5th Edition tries quite hard to bring non-magical characters up to par with their spell-slinging counterparts. The main way it does that is simply reducing how absurdly well casters scale into upper levels, mainly by requiring them to expend higher level spell slots to make their spells more powerful. Magic Missile, cast as a 1st level spell, will always make 3 missiles, regardless of your caster level; if you want more unblockable magic damage, you need to spend a higher level spell slot (e.g. a 3rd level Magic Missiles would have 5 missiles). Spellcasters also receive much fewer high level spell slots (e.g. at maximum level, a full caster such as a Sorcerer will have a single 9th level spell slot).


The other side of this reduction in magic potential is that magic items are both rarer and less powerful. Weapon enchantment bonuses cap out at +3 (even for artifacts like the Holy Avenger). The Hammer of Thunderbolts is a +1 weapon in 5th Edition. That is the kind of low magic campaign we're talking about.


Spellcasting Progressions

Oh and while we're on the subject of magic, spellcasters all behave like Sorcerers now. Memorization-based spellcasters (such as the Wizard) still choose a subset of spells from either the spells they know or their spell list (although they can swap which spells they are considered to have memorized each day), and spontaneous spellcasters simply have access to all spells they know. The flip side of this is that you can use your higher level spell slots to cast spells you have prepared for lower levels.





Yes, yes Aqua, this is all great, so what have you actually implemented?


Well, a lot of stuff.


I have racial bonuses, as listed here:



Racial Bonuses

Human: +1 to all ability scores

Half-Elf: +2 Charisma, +1 to two other ability scores, advantage against charm effects, immunity to magical sleep effects, +1 bonus to movement speed, infravision

Elf: +2 Dexterity, +1 Intelligence, advantage on Perception checks, proficiency with light blades and bows, advantage against charm effects, immunity to magical sleep effects, +1 bonus to movement speed, infravision

Dwarf: +2 Constitution, +1 Wisdom, advantage against poison effects, resistance to poison damage, proficiency with axes and blunt weapons, +1 hit point per level, -1 penalty to movement speed, infravision

Gnome: +2 Intelligence, +1 Constitution, +2 bonus to speed factor, advantage against magic, +1 lore per level, -1 movement speed, disadvantage with heavy weapons, infravision

Halfling: +2 Dexterity, +1 Charisma, +2 bonus to speed factor, +1 luck bonus, advantage against fear effects, advantage on Stealth checks, -1 movement speed, disadvantage with heavy weapons

Half-Orc: +2 Strength, +1 to two other ability scores, proficiency with heavy blades and spiked weapons, critical hits deal an additional die of damage, infravision




I have a mostly functional advantage/disadvantage system implemented that can be accessed through setting various splstates.


I have a revamped weapon proficiency system that groups weapons into 10 martial weapon classes. This system also allows spellcasters to get bonuses to their makes spell attacks (such as Shocking Grasp). Furthermore, this system leaves about a dozen open proficiency slots that could be used to introduce new weapons or weapon groups.


I have a couple classes and kits from PnP 5th edition converted to 2nd Edition, as listed here:




Hit Die: d10

Armor: Any

Shields: Any

Weapons: Any

Saving Throws: Strength and Constitution

Kits: Champion, Eldritch Knight


Fighting Style: Pick one of several fighting styles, gaining benefits such as +1 AC, a bonus to damage with ranged weapons, or bonuses from various modified weapon styles.


Second Wind: Once per day, regain hit points equal to d10 + your level.


Action Surge: Once per day at 2nd level, you may act for an additional round while others remain frozen in time. An additional use is gained at 17th level.


Extra Attack: At 5th level, you may make two weapon attacks per round. This improves to three attacks at 11th level, and four attacks at 20th level.


Indomitable: Once per day at 9th level, gain advantage on all saving throws for 1 round. Additional uses are gained at 13th and 17th levels.



Champion [Kit]

Improved Critical Chance: At 3rd level, gain a +5% bonus to critical hit chance. This improves to +10% at 15th level.


Remarkable Athlete: At 7th level, you may add half your Strength modifier to your movement speed.


Additional Fighting Style: At 10th level, you may select a second Fighting Style.


Survivor: At 18th level, you regain hit points equal to 5 + your Constitution modifier each round while you have less than half of your hit points left.


Eldritch Knight [Kit]

Arcane Spellcasting: At 3rd level, you are able to cast a small amount of Abjuration and Evocation spells, as well as several Wizard cantrips of your choice. Your spellcasting improves as your Fighter level increases.


War Magic: At 7th level, whenever you use a cantrip, you gain +1 Attack per Round for 1 round.


Eldritch Strike: At 10th level, your successful attacks impose disadvantage against spells for 1 round to the target.


Arcane Charge: At 15th level, while you are using Action Surge, your movement speed is doubled.


Improved War Magic: At 18th level, whenever you cast a spell, you gain +1 Attack per Round for 1 round.


will add more soon...




Is this a mod that people would be interested in (or would like to assist with)? Are there features you would like to see? How do you feel about what I've shown above? Opinions? Comments? Criticism? Ideas?

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It's misleading to think the game is based on the 2nd edition of the Advanced Dungeons and Dragons. It's not.

It's actually a Real Time Strategy game, unlike the 5th edition that has this thing called ROUNDS/TURNs. Yes, the descriptions say rounds and turns... but the game has no standard turns, just ticks the engine counts ... and shows animations between them, as the game runs actually in 30 frames per second and that's 15 ticks. Where the AI reads all the set variables and then writes the results, and then reads..... Just like any RTS game does.

And the Resistance thing is total BS, as we can set it to 50%, 100%, 0% -50%, and to 1%, 2%, 3%, 4%..... ETC Why the cheese would anyone go back. Yes, in an pen and paper system it's easier to revert back to easy numbers, but it's not so good in a CRPG that is a RTS game. Ouh by the by, what's 50% out of 3 damage ? Is it 1 or 2, and why it's not 2 or 1 ?

"+1 bonus to movement speed... -1 movement speed..." ... right, tell me, have you actually played the game through with multiple characters that have different movement speeds. Eventually it will get very unfun, as you'll actually have to move the characters over large maps to get to certain places.


"+2 bonus to speed factor", well that happens to only effect the HUGE weapons, as the small ones have ~0-1 speed factors anyways. And one can have only one item that effects their speed factors anyways besides the weapon itself, as it's very hard to get them stack.


"DC 20 roll" you do understand that the game actually has no Difficulty Checks, just AC, Thac0, Save Throws and rogue skill difficulty levels. The ToBEx and EE games feature the Concentration checks. But there's no Checks of knowing stuff like history, religion, arcane, social interactions or anything like those, apart from a few stat checks that have no d20's as rolls. Well, not at least if you don't mod them in.

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In order:


- a round is 6 seconds of game-time; a Turn™ is 1 minute (10 rounds), but the term is often used to refer to a round.


- Having four options for resistance streamlines it. Is simpler necessary worse? And if so, why?


- The whole "how do you round?" thing is arbitrary, because the same argument could be made for almost any number. What is 4% of 20? is it 0 or 1? Why isn't it the other? On an engine side, it probably either says "round down" or "round to even" and both are acceptable.


- I have actually played the entire saga through with an otherwise unmodded Monk. Power imbalance between characters was much more frustrating than the movement speed bonus. That is not to say that I'm particularly attached to them, but they are a slight balancing mechanic.


- Speed factor is mostly thematic, but if you factor in how 5E handles weapon speed (which I have done), the typical weapon has a speed of 5. Light weapons (which are the fastest) have speeds of 3, so a Gnome/Halfling wielding light weapons would have a speed factor of 1, which would make them able to interrupt low level spells. (Other rules state that two-handed or heavy weapons each add +2 to base speed factor and crossbows have +5, so the breakdown is light: 3; [null]: 5; two-handed OR heavy: 7; two-handed and heavy: 9; crossbow: 10).


- The "DC 20 roll" was an example of how bounded accuracy in 5E works. Furthermore, there are plenty of d20 rolls in the IE games, they're just presented differently. Checks to hit, saving throws, etc. are all d20 roll based.


- On the subject of Saving Throws (and other conversions) WotC actually released a helpful guide for converting 2nd edition to 3rd edition. 3rd edition and 5th edition rely on a lot of similar mechanics, so it is pretty easy to go from save DCs and bonuses to "roll above this number". I believe the general rule is 15 - [3rd/5th edition modifier] = [2nd edition base save value].

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- The whole "how do you round?" thing is arbitrary, because the same argument could be made for almost any number. What is 4% of 20? is it 0 or 1? Why isn't it the other? On an engine side, it probably either says "round down" or "round to even" and both are acceptable.

Erhm, no... in this game, the game mechanisms rule. In Pen and Paper games, it's universally ruled by the House Rules, so 50% resistance to fire is either always rules up or down, never to the nearest next digit with random digital dice because of game mechanisms.


- Having four options for resistance streamlines it. Is simpler necessary worse? And if so, why?

Well, when you make a dragon that has 50% fire resistance, it needs 175+ hitpoints to not get pulverized by say 12 fireballs. At 90% resistance, it needs a lot less hit points to do the same, as 40 Hit points covers the whole lot. Why 12... that's 12 seconds of combat for 6 mages(that are at level 10, as they do 6*6d10 *2=~190).

This is partially why the 5th editions monsters don't belong to the "2nd edition games", it's simplified, and thus their stats are astronomical. Or just like Spell Revisions. Which has OP has hell summons, cause they OP the normal characters by miles, and the in game assets by light years. Which just makes bringing the 6 mages to the game that much more "profitable".

Ouh, and in the 2nd edition games, the characters stats won't be at <20 unless they do so under a special circumstance. A level 20 fighter won't automatically have <STR 20. That came in the editions after the 2nd.

So you want to make the walk speed an absolute horror... well go a head. It's not likely that players will be pleased with it.


And like I said, the game is not actual a 2ed edition game(although some of the creatures might be from it), and so considering it as such is the biggest mistake. It's an adoption of the rules, not a game based on them.

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To be honest, how is a meta discussion of rounding and whether the engine is a true implementation of 2nd edition rules relevant to the mod proposal as a whole. Seems like the bones you have to pick with those things aren't necessarily unique to the mod I'm discussing here.


My point re: rounding was that I don't really care too much how the game rounds assuming it is consistent. More importantly, how the game handles rounding is not relevant to how the 5th Edition ruleset project would proceed.


The movement speed thing is fair, and looking at it I will probably remove it.


The mod itself would be comprehensive, it would address both player characters and monsters. High level 2nd edition monsters would shred high level 5th edition characters and most 5th edition monsters.


And if you're trying to fireball a red dragon (which is immune [100%] to fire in all editions I can find references for) to death with glass cannons, you deserve however many chunked party members you get.

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I just told how I felt about the concepts... of course, you HAVE to be free to think for yourself.

..The movement speed thing is fair, and looking at it I will probably remove it.

You might want to make a component that's has the Movement speed modifiers separated from the main component, so the player has an option to enable it(or not!).


And if you're trying to fireball a red dragon (which is immune [100%] to fire in all editions I can find references for) to death with glass cannons, you deserve however many chunked party members you get.

The trouble is, it's not a red dragon. It can be a green and still have more than 50% fire damage resistance. Or a 5% less. As you can see, that's the whole argument.


Now of course I have been the only one to write to you, and complain.. don't take it as the only opinion out here. So I'll encourage you to upload the files when you have them available AS IS(how ever you decide to make them), first .. and maybe then take in the criticisms I have .. with every other that's out there.

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Okay down, Imp, down! You're pre-emptively killing what could be a good thread. Let other people participate.


Frankly I love this idea in orinciple, and I love a lot of those rules in principle. BUT I feel like the implementation would make this incompatible with pretty much every other mod out there.


Maybe a more limited-scope mod, putting a "5E gloss" on the infinity engine? That could be cool. Simplify resistances (god knows the game needs that), add in the advantage/disadvantage mechanic (very cool), bounded accuracy sounds great (and should be super easy), and simplifying weapon proficiencies is doable. Changing saving throws is possible - I have useful .tp2 code for that - but changing their names opens up a big can of worms.


Changing weapon enchantments is very possible - again, I have code that could very easily be adapted. Changing spell tables to make high-level spells rare and powerful and low-level spells more spammable is a great idea - I always do that in my personal games. But using high-level slots to cast lower level spells, and to give wizards halfway-semi-non-Vancian spellcasting would be a) very difficult to implement for the player, and b) nigh-impossible to implement for the AI.

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a) ... and b) nigh-impossible to implement for the AI.

Right... have you ever ran to an enemy that has ran out of magic missiles ? While they didn't want to cast Time Stop(first). So gather your intelligence and drop that thought. It's optimizing the AI that that's about.

Then we come to the a). The game has an opcode to restore spell levels, so that won't be the problem, but targeting which spell to forget will be harder. Unless you go back and implement the mana based memorization, just like this mod did, or use the same system I edited for the Foundling, mage kit that based it's casting to unique spells all of it's own, the system was there already(it was probably based on the mod I mentioned), I just made a very few tweaks so that the NPC and it's kit was able use it correctly ... but you could as well make just more Sorcerer kits and forget the idea in the first place. For example by adding learned Metamagic spells. Level 2 Magic Missile, a spell that cast two Magic Missile spells ... for Invoker type Sorcerer. etc.

The simplest way to do this is to all the Specialist Mage-Sorcerers is to give them one meta spell. Like for example, the Magic Missile x for Invoker, Conjurers actually have their Meta Magic spell, Summon Monster x, with the original creatures. Illusionist could have Reflect Image, Mirror Image, Invisibility 10'Radious etc.

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If by "harder" you mean "utterly impossible" then yes, I agree.

It shouldn't be impossible to make an AI creature that reacts to a spell being cast by noting it's level, using the script trigger 0x0091 ... a spell that has 99% likelyhood of failing as conjuring the AI'ed creature sets the casters failure rate to be that 99%. Which is done by an infinite use innate.
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subtledoctor, I had thought about the possibility of doing a more overlay-type (?) mod. That could still work quite nicely.


Basically, it would require:

- flattening THAC0 and save progressions

- revisions to weapon proficiency, weapons, and armor

- changes to spells per day tables

- addition of the advantage and resistance system and revisions to spells/items/abilities to make use of it

- changes to spells themselves to not scale with level

- changes to monster defensive stats so as to not be impossible


Note that the changes to spells per day tables would require a little bit of work if Mages functioned as they do now (instead of as pseudo-Sorcerers as Wizards do in 5th Edition). It'd probably require giving Mages more spell slots than Sorcerers to make up for their lack of on the spot versatility (which to be honest might not be a horrible idea anyway...). To clarify, if Mages and Sorcerers had the same amount of slots per day, but otherwise functioned identically, Sorcerers would be better able to use more conditional magic effects, while Mages would have to stick to spells they know they would get value from.

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