2) Paper Dungeons and Origami Dragons
(Yes, "origami dragons" is a reference to Hooktail.)
To convert Paper Mario's battle system into a text-based RPG, I had to change a few things. There are inherent differences between using a controller and merely speaking out your desired actions. The latter may be more variable, but Paper Mario's famed action commands are not really possible in a text-based medium. The closest you could get would be to flip a coin (or roll dice) to determine the outcome of the command instead of pressing a button at the right time or whatever, but the problem is, timed button presses are an acquired skill, whereas using probability devices like dice means leaving the results up to chance. That's the inherent difference: chance versus skill. You can increase the probability to simulate an increase in skill, but it's not the same thing, because probability increases of that kind are more akin to in-game stat increases than real-world skill increases. You don't necessarily get better at playing a game at the same rate that your character gets stronger, or even in the same way.
So what are the differences between the Paper Mario number system and the Arpeggio one?
Action commands. There are none. Instead, I have designed the system so that a "basic attack" deals the kind of damage that you would expect to be dealt from an attack where the player misses the action command, but if the character attacks using a weapon, or uses a weak special attack, then the damage dealt is x2, which is what you would expect if the player nails the action command. There are variations in this—each special attack is unique, and some weapons deal more or less than x2 damage, but the principle is present. Of course, this means that attacking with a weapon is kind of like rigging a controller to guarantee perfect action commands, but this is comparable to Paper Mario's own elimination of accuracy, allowing all attacks to strike without fail under normal circumstances. The most common amounts of damage to be found in Arpeggio (dealt by either unarmed special attacks or armed basic attacks) are x1, x2, x2 +2, and x2 +4; the typical "ultimate" amount of damage is x4.
Types of attacks. In Paper Mario, a lot of the battle strategy revolves around the differences between Jump-type attacks and Hammer-type attacks. Although Arpeggio differentiates between melee and projectile attacks, I want the players to have the freedom to design any kind of attacks that they want, stylistically speaking, and so to restrict them to attacks resembling Jump and Hammer is no good. Therefore, Koopa-like enemies can no longer be flipped onto their backs (which was kind of the primary difference between Jump and Hammer). Also...
Enemy positioning. This was the other difference: Hammer could only reach the first enemy in line, but he could be Jumped over to reach the others. Also, flying enemies couldn't be Hammered, and ones clinging to the ceiling couldn't be Jumped on either, and had to be hit with earthquakes or flying partners. Although Arpeggio incorporates flying characters' weakness to bows (from Fire Emblem) and immunity to earthquakes, for the most part, any attack can be used on any character. This is because relying so heavily on spatial positioning in a non-visual medium is not very practical. Edit: I have now at least made it so that melee attacks cannot be used on flying characters unless the attacker can jump high enough (based on a field stat; see below), bringing back a little nod to some of Paper Mario's strategy. Edit #2: Bug Fables introduced the idea of enemies that burrow underground, which is a more readily accessible third position than Paper Mario's enemies who hang from the ceiling, so now I've got that too.
Types of attacks. I know, I already said that. But while failing to utilize the differences between Jump and Hammer, Arpeggio does make other distinctions—most importantly, psychic attacks. Along with Attack Power and Defense Power, Arpeggio features Brain Power, which is used as both attack and defense for psychic attacks. This idea—one stat being used for both offense and defense—is present in many RPGs, but seems to me to make the most sense as a psychic stat. Arpeggio also features Magic Power, which determines the strength of magical spells, but still works against the same Defense Power stat that Attack Power does—unlike in Fire Emblem or the modern Pokémon games, where it would get its own different defense stat, often called "Resistance."
Fuel points. In Paper Mario, both Mario and his partners use the same pool of Flower Points to fuel their special attacks. In Arpeggio, since there is a different player for each player character, each character has its own fuel points. There are also two types of fuel points per character: VP (Vigor Points) and MP (Magic Points). VP is quite like FP from Paper Mario, fueling a variety of special attacks including psychic attacks, but all magical attacks are fueled by MP instead. This is to create a bit of variety, similarly to using Brain Power as both defense and attack, but here psychic attacks share the quality with other attacks, while magic attacks get the unique aspect. This variety creates advantages and disadvantages to each type of attack—for example, many enemies with high Defense Power have low Brain Power, so are susceptible to psychic attacks; however, psychic attacks use VP, which means that if a character's VP is used up, the character cannot use regular special attacks, either. If the character uses magic attacks, VP is saved up for regular actions. It is also rarer for enemies to drain MP than VP—at least in Game 1.
Types of attacks. I'm just trying to make sure you're paying attention. This time, I mean Elements. While it is true that in Paper Mario, some enemies will be immune to, say, fire-based attacks, or else they will take extra damage from them, there are very few elemental attacks of this nature, and also very few elements present. Arpeggio uses a system of Elements more akin to the system used in the Pokémon games, except adjusted back to work with Paper Mario numbers. Multiplication (beyond the x2 equated with action commands) does not work very well in the Paper Mario number system; typically, in the first two Paper Mario games, enemies who take "extra damage" from a certain attack are specifically taking +2 damage (there was an exception in the first game, where Dry Bones would take +10 damage from fire or explosions), whilst there is no such thing as a mild resistance against an attack, only a full immunity. In Arpeggio, there are eight Elements, and a character may be either weak (+2 damage), resistant (-2 damage), immune (x0), or have a super-weakness (+5) to any of these Elements. Unlike in Pokémon, each individual character has his or her own Elemental Modifiers that determine damage taken, instead of each character belonging to an elemental class that determines these weaknesses and resistances. Many characters also have no weaknesses or resistances, in which case the Elementality of targeting attacks has no effect on the character.
Leveling up. In Paper Mario, Mario grows a level whenever he earns 100 Star Points, and one level up allows the player to increase HP by 5, FP by 5, or BP by 3. Since it is safe to assume that fewer total battles will take place in a text-based RPG than a video game, player characters only need 20 experience points to level up in Arpeggio; a level up allows them to increase either HP, VP, or MP by 5. This last part differs from Paper Mario in that HP, FP, and BP are all useful, whereas a player character in Arpeggio can easily choose to focus on VP or MP exclusively and ignore the other, meaning that HP and the one being used will go up that much faster than in Paper Mario where all three stats must be given attention. This, I am hoping, will also be balanced out by the inability to accomplish as much in a text-based RPG compared to a video game.
Attack/defense increases. Actually, the idea is to make these pretty close to Paper Mario—in the game, Mario's Jump Attack Power increases by 1 whenever he gets a new pair of boots, whilst his Hammer Attack Power, as one might guess, goes up by 1 with the acquisition of a new hammer. The important part is that Mario's Attack Power and Defense Power do not increase through leveling up, as they would in most RPGs. This allows the enemy HP numbers to remain very small and understandable, and is, I now believe, the key to keeping Paper Mario's numbers magical. Therefore, I have tried to retain it in the Arpeggio system—but some changes were necessary. Mario is not required to increase his Defense Power in Paper Mario, although there is a Badge that allows him to do so; since Arpeggio does not use Badges, and features Magic Power and Brain Power in addition to Attack Power and Defense Power, the idea is for the Maestro to create infrequent but consistent opportunities (preferably at the end of each story arc) for each of the player characters to increase one of these four stats of their choice. It is my hope that whether they increase an offensive stat or a defensive one (Brain Power even has both qualities), this will still balance out in the game mechanics; essentially, it is the responsibility of the Maestro to feed the players enemies whose stats match the player characters' attack and defense numbers, as well as to assign appropriate experience point values to these enemies.
Field stats. Obviously, this is a completely different thing than Paper Mario. Of course, you do gain new field abilities throughout Paper Mario and the other Mario RPGs, but field stats in Arpeggio do not actually change. The six field stats in Arpeggio are very similar to those found in Dungeons and Dragons, but the opportunity for a unique field ability is taken directly from Paper Mario—it is based off of the field abilities of Mario's partners. In designing video games that feature multiple playable characters, I have found it essential—indeed, fundamental—to make sure that each character has at least one ability that allows him or her to accomplish something that none of the other characters can accomplish. In such video games, this assures that the single player will make use of the entire cast of playable characters; in a text-based RPG like this, it assures that each of the different player characters (who are each controlled by a different player) will add something essential to the party (unless that player opts not to create such an ability, in which case the character's normal field stats will theoretically be slightly better than everyone else's, and since field stats never increase, this might be useful as well). Unique field abilities, as noted elsewhere, should be intentionally incorporated into the game's field puzzles by the Maestro, the more often, the better. Edit: I've now added a Weight field stat; this does not interfere with the original field stat creation system, but for you sticklers who will note the reference to "six" field stats at the top of this paragraph, here is your corrective footnote.