Fate/Extra Solver

Combat solver for Fate/Extra

Building

You need Rust & Cargo (or just Rust with the crates specified in Cargo.toml).

To get, build, and run just:

git clone github.com/RaineForest/FateExtraSolver.git
cd FateExtraSolver
cargo run

For those Windows folks, I've included a binary in the root.

Problem description (for those not aquainted)

Fate/Extra is an RPG developed by Type-Moon for the PSP. The combat is very rng-based and requires quite a bit of memorization later in the game.

The combat is structured like this:

Both sides choose 6 actions to perform per round
Actions include: attack, guard, break, specials
Guard beats attack, break beats guard, attack beats break (rock-paper-scissors style)
Specials don't have a weakness per se, and they beat everything else at a mana cost, but can be beaten by rpg stats in the event of competing specials
Based on the number of enemies you've beaten of a certain type, a few actions in the string are given to you.

Since enemy attack patterns are fixed, although numerous, we can do some statistics and pattern matching to determine the "best" response.

Solution

Taking known enemy patterns and a given string of actions, it can determine the best course of action based on how risky you'd like to play the game. I made a shell type entry format for solving, considering that someone would be playing the game for long stretches and wouldn't want to enter a long command for each round. The commands supported are as follows:

select - selects the enemy to solve against
solve - determines the best pattern to respond with
threshold - set the riskiness factor (lower values are safer)
list - lists the loaded enemies
help - lists commands in the shell
exit - exits the program

Example:

$ cargo run
    Finished dev [unoptimized + debuginfo] target(s) in 0.11 secs
     Running `target\debug\fate_extra_solver.exe`
> select Inspire
> solve _ G _ _ _ _
Guard   Break   Break   Break   Guard   Break
> threshold 40
> solve _ G _ _ _ _
Break   Break   Break   Break   Break   Break
>

File details

src/main.rs: Command dispatch and shell logic
src/enemy.rs: Enemy structure and solving utility functions
src/enemy_builder.rs: Reads enemies.txt and generates a map of Enemys
src/action_count.rs: Utility structure for keeping track of statistics
src/action.rs: Action enum and simple trump/weak definitions
enemies.txt: Enemy action tables

A bit more about `enemies.txt`

It's got a simple, human-readable format for easy editing. Enemy names start at the start of a line and end in a colon (:). Following that are the action sequences for the enemy. The action sequences consist of four different letters: A, G, B, or S for Attack, Guard, Break, or Special, respectively.

Example (or just look at enemies.txt for yourself, but y'know, spoilers):

<Name>:
<Sequence of 6 action initials [A, G, B, S]>
<more sequences>

<Another Name>:
<more sequences>

Todos

A lot of the action data is still incomplete or inaccurate... I could use some help here, especially from a more authoritative source than just playing the game and writing down patterns that you run into. I tried extracting from the game's files and I couldn't find anything helpful.

If you find something wrong, please make a pull! Don't just abide, man!

enemies.txt was designed to be easy to edit!

Also, I haven't played Fate/Extra CCC yet, but if the combat is the same, I'd like to extend this to that.

A GUI would be nice, but right now I'm not willing to put up with Rust to make it happen.

Thanks

http://www.aegisgames.net/guide-fate-extra-enemy-patterns/

https://www35.atwiki.jp/fate_extra/pages/1.html (Google Translate is helpful here as well)

RaineForest/FateExtraSolver