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Rosa is a tool to generate step routes for the SNES/SFC release of Final Fantasy IV. Step routes are specific walking patterns designed to manipulate the timing and details of random encounters. They are primarily used for speedrunning the game. Additional details can be found at

GitHub release (latest SemVer) C++


Rosa requires meson, Boost and LMDB to be installed on your system.

Currently, if building from a tarball, submodules will not be available and will need to be copied to the external directory manually. If building directly from git, you should ensure submodules are initialized before building. The following third-party submodules are required:

  • CLI11, a C++11 command line parser, released under a 3-clause BSD license.

  • cpp-peglib, a C++17 PEG library released under the MIT license.

  • LMDB++, a C++17 wrapper for LMDB released under the Unlicense.

  • tsl::sparse_map, a memory efficient replacement for std::unordered_map released under the MIT license.


Rosa makes use of C++17 (and potentially beyond) features, so it requires a modern compiler to build. It is currently tested with g++ 8 and clang++ 10. Slightly older versions of clang++ may work as well.

To build the executable, enter that main directory and execute the following:

mkdir build
meson build
cd build

To run the executable, you should return to the main directory as your working directory, as Rosa expects data files to be in certain locations.


src/rosa [OPTION...]

No options are strictly required, as there are sane defaults for all options, but some minimal options should be set to get any sort of real use out of the software.


-r, --route

Specifies the route definition for which to generate a step route. This file should be named and located in the form data/routes/%ROUTE%.txt where %ROUTE% corresponds to the given route name. More details about the format of this file are available later in this README.

-s, --seed

Specifies the seed for which to generate the step route. This should be an integer from 0 to 255 (inclusive).

-m, --maximum-steps

Specifies the maximum number of extra steps a route can take in a given segment. Zero is a slightly special value that disables all optimizations.

-n, --maximum-step-segments

Specifying this parameter enables a special mode where the number of segments where extra steps can be taken is restricted to the given number. This will generally lower overall performance, especially once you start getting into the 10+ range. However, it is faster for smaller values, and any persistent cache is reusable across runs, regardless of how the parameter is changed. This allows you to generate routes quickly that use a few locations, and then refine those into more complicated routes. Do note, however, that the total time taken by multiple runs in this fashion is slower than a single run. It is, however, faster to use a preexisting cache from a faster run than to go entirely from scratch.

-v, --variables

Specifies values for the given variable indices. The format is a:b c:d... where a and c are indices and b and d are values. In addition, a range of values can be specified by appending a hyphen and an additional number (e.g. a:b-c).

-t, --tas-mode

Adjusts the optimization to use TAS-specific features. This currently only uses the minimum encounter timings instead of the average, but additional features are planned.

-p, --prefer-fewer-locations

When the maximum-step-segments option is configured, this option enforces that routes will always use the fewest locations possible to take steps that still gives the optimum result. The default behavior is instead to prefer taking every step as late as possible. Enabling this option will increase runtime to some degree, as it requires calculating additional states.

-c, --cache-type

Sets the type of cache used. There are two options available: dynamic or persistent. The default is dynamic, which will cache all states in memory, discarding the data when complete.

The second option is persistent, which, in addition to an in-memory cache, saves the data in a persistent database on disk. Rosa makes no attempt to manage the lifetime of this cache, and you are expected to know what you are doing. The primary purpose of this option is to persist the database for use in repeated runs (potentially fixing only the first variables in a route). Performance is too degraded to recommend for any other purpose, especially if the entire database cannot fit in memory. When using this cache, if the route definition changes or parameters are modified, using an existing cache can result in suboptimal generated routes. The current maximum size of this database is 128GB. While none of the default routes should exceed this, the no64-excalbur route is close to the boundary.


If using a persistent cache, controls the directory where the cache is located. The default is cache/. Each route/seed combination will automatically use its own individual cache. There is not expected to be significant overlap between seeds. If you wish to start with a fresh cache, you should delete the relevant directory manually.


If using a persistent cache, directly specify the name of the directory where the cache will be located. The directory will be created if it already exists. As with the previous option, this location will be created it if it doesn't exist, and will never be deleted automatically. If specified, this option overrides the previous option.


If using a persistent cache, determines the size of the in-memory cache. The default is system-dependent, but should be at least 2^31 - 1, which will most likely result in the database being kept entirely in memory. Values are written to memory and the persistent cache simultaneously, and keeping the in-memory cache is a performance optimization.

File Formats

Field Definitions

There are a few fields that are mostly free-form strings, but the code may make assumptions about their values and format. These are defined below. Deviating from these formats may or may not work, and the ultimate behavior is undefined.

Party Specification

A party is indicated by a 20-character string, with each character representing the following:

  1. The number of party members in the front row. Must be either 2 or 3.

  2. An indication of whether or not the party current has GP. Should be - if not or G if they do.

  3. An indication of whether or not this party is on a world map. Should be - if not and + if they are.

  4. Characters 4-18 consist of 5 sets of 3 characters. The first character in each set is any letter from A-Z, with a capital letter designating an alive character and a lowercase letter designating a dead one. The following two characters are the agility of the character in decimal form.

  5. The last two characters are the average party level, in decimal form.

Variable Name

Variable names are hexadecimal numbers designed to be used partially as if they were strings. Any hexadecimal number is technically a valid variable name, but the included routes are standardized on the following format:

The first digit should be a letter from A to E, specifying the type of variable. The only currently used letters are C for a choice or E for extra steps.

The next four digits correspond to the related map number, as defined in the map definition.

The final two digits are an index, in case that particular map has more than one variable.

Encounter Formation Specification

This file defines the encounter formations and their groups. The only currently available data is for the USA release of Final Fantasy II. Custom data sets can be created by the user, however.

These files live in the data/encounters directory, and consist of tab-delimited lines. Note that all fields must be filled. If a field needs to be empty, a - should be used. The two types of lines are:


This line defines a particular encounter formation. The six fields are:


  2. A number from 0 to 511 indicating the formation number.

  3. A textual description of the encounter. This can be omitted if this formation number has already been assigned a description earlier in the file.

  4. The party for which this particular line provides data.

  5. The average duration of an encounter in frames, specified as a decimal with three digits after the decimal point.

  6. The minimum duration of an encounter in frames, again specified as a decimal with three digits after the decimal point. In this case, those three digits should be zero.


This line defines a group of formations. The fields are:

  1. GROUP

  2. The number of the group, ranging from 0 to 255.

  3. A tab-delimited list of eight numbers indicating the formation numbers that are in this group. They need not be unique.

Map Specification

This file provides data about the maps available in the game. Similar to the encounter formation data, this file currently contains data for the USA release of Final Fantasy II, but custom data sets can be created by the user.

The file is located in the data/maps directory and consists of many tab-delimited lines, with lines conforming to the below format:


This line defines a map. The fields are:

  1. MAP

  2. The map number, consisting of four hexadecimal numbers. For dungeon maps, this should be 3 followed by the three-digit map number. For overworld, underworld, and lunar maps, the first digit should be 0, 1 or 2 respectively. The final three digits should refer to unique map regions.

  3. The encounter rate of the map/region.

  4. The encounter group of the map/region.

  5. The title of the map. This string is currently unused in the software, but is intended to be the on-screen description of the map when entering.

  6. The description of the map. This should be a complete textual description of the map, sufficient to adequately distinguish it from any other map.

Route Definition

Route definition files live in data/routes and are named according to the short name for a route (e.g. paladin.txt for the Paladin% route).

They consist of many lines which provide information about the route. Like the other files, each line is a tab-delimited line. In addition, the file is limited to a maximum of 65536 lines (not including empty lines and comments). The program is not incredibly robust, and if your route description is malformed in some way, the program will likely crash.

There are numerous different lines, which will be described in the following sections.



This line provides the name of the route, and consists of ROUTE followed by the name.


This line provides the route version. This should be VERSION followed by an integer, ideally incremented after every change.


This line determines which data set to use. The default and standard is ff2us, which describes the maps and encounters of Final Fantasy II (USA). Custom data sets can be created by creating the appropriate files in the data directories.

Standard Types


This is a line which will generate extra output, usually to help describe a location or indicate the position of a boss battle. The two fields are:

  1. NOTE

  2. A string with the desired extra output.


This line changes the currently active party. The two fields are:

  1. PARTY

  2. The new party, as a 20 character string as defined above.


This is the primary line type. It consists of the following fields:

  1. PATH

  2. A 7-digit hexadecimal number representing the variable name for this segment. If extra steps are not allowed in this segment, this should be -.

  3. The 4-digit map number, in hexadecimal.

  4. The number of tiles traversed on this segment.

  5. The number of required steps on this segment.

  6. The number of optional steps on this segment.

  7. The number of transitions from map to map on this segment.

  8. A + if single extra steps are available, and a - if they are not.

  9. A + if pairs of extra steps are available, and a - if they are not.

  10. A + if this segment can take an extra steps for free when saving, and a - if not. This is a TAS-specific feature that currently has no relevance in the software.

  11. A number of frames (can be floating point) to apply as a penalty to the first encounter in this segment. Must be determined experimentally for the desired segment.


These three lines are used to define branching in the route. (For instance, to enter a side room and take extra steps. There is experimental support for nesting these, but this feature has not been thoroughly tested.


This line indicates that there are multiple options on how to proceed. The line has the following fields:


  2. A 7-digit hexadecimal number assigning the relevant variable name. Assigning a variable name of - will essentially make it impossible to reach any option other than the first one.

  3. The number of options available.


This line indicates a new option begins (and any previous one ends). It has the following fields:


  2. A free-form string describing the option in as much detail as necessary.


This line signifies that the final option is ending, and normal non-optional segments begin.

Encounter Searching

This lines provide a facility to search for a particular encounter or set of encounters (e.g. for a grind fight).


This line defines that an encounter search is beginning. It has the following fields:


  2. A string with a description of the search.

  3. An expression listing the desired encounter numbers to search for. The expression can contain up to 48 terms. The terms can be separated by any of three operators: + will require that both operands occur. | will require that one of the two operands occurs. > will require that the first operand occurs followed by the second operand. The operators can be used in any combination. The order of operations is +, |, followed by >. However, it is also possible to group them in any desired pattern with parentheses. For example, (2+3)|(5>7) would require either both encounters 2 and 3 or encounter 5 followed by encounter 7. Due to the way these searches are processed, certain combinations of values where + has operands consisting of groups with | will not operate as expected. It is recommended to refactor these to ensure the + operator is the innermost.

  4. The new party formation after the conclusion of the fight. This is somewhat limited, in that in the case of multiple fights, it might be desirable to list a new formation after each. However, this is not currently possible.


This line signifies that the encounter search is over. This allows a search to span multiple maps. The final map in a search must have an associated variable name, as if the encounter has not been found, extra steps will be forced until it is.



Many of the original ideas for Rosa came from work done by the_roth and Myself086 with their own step routing work. This work was originally synthesized into a previous version of this tool, Spoony.

Eventually, various limitations of the Spoony architecture (primarily its inability to generate routes that were guaranteed optimal) came to light. Rosa is the culmination of a near-complete refactoring of the Spoony codebase to support an optimal solver. Early experiments with the new solver were undertaken under a separate Rosa project that is now defunct. The optimal solver incorporates ideas from fcoughlin's independent implementation of a step route optimizer, ff4step. Additional features to the route definition format have since been added, necessitating this release of Rosa.

The entire FF4 speedrunning community has been incredibly supportive, not only by providing information and by helping with research, but also by actually using the generated routes in runs to help prove their viability and accuracy.


Rosa Optimizes Steps Automatically: Final Fantasy IV (SFC/SNES) Step Route Generator





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