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Netskrafl - an Icelandic crossword game website

Join the chat at https://gitter.im/Netskrafl/Lobby

English summary

This repository contains the implementation of an Icelandic crossword game in the genre of SCRABBLE(tm). The game, which is free-to-play, is accessible on the web at https://netskrafl.is.

Screenshot from mobile UI

The game backend is implemented in Python 3.8 for the Google App Engine Standard Environment.

The frontend is a tablet- and smartphone-friendly web client in HTML5 and JavaScript connecting via Ajax to a Flask-based web server on the backend.

The game contains a robot crossword player written in Python. The algorithm is based on Appel & Jacobson's classic paper "The World's Fastest Scrabble Program". At maximum strength level, the robot always plays the highest-scoring move possible but additional and alternative strategies can be plugged in relatively easily. At the lowest strength level, the robot is limited to a set of common words, about a quarter of the size of the entire word database.

The software has a range of features such as immediate tile-by-tile feedback on word validity and score, real-time synchronized games with clocks, Elo scoring of players, an online chat window, and the ability to view player track records.

The game uses a word database encoded in a Directed Acyclic Word Graph (DAWG). For Icelandic, the graph contains almost 2.3 million word forms. Further information about the DAWG implementation can be found in README.md in the Skrafl repository on GitHub.

The game mechanics are mostly found in skraflmechanics.py.

The robot player is implemented in skraflplayer.py.

The DAWG navigation code is in dawgdictionary.py.

Language-specific tile sets, bags and vocabularies are handled in languages.py.

The main Flask web server is in netskrafl.py.

The Game and User classes are found in skraflgame.py and skrafluser.py, respectively.

The persistence layer, using the schemaless App Engine NDB database, is in skrafldb.py.

The client JavaScript code is in static/netskrafl.js.

The various Flask HTML templates are found in templates/*.html.

The DAWG-compressed vocabularies are stored in resources/*.bin.dawg.

To build and run locally

Follow these steps:

  1. Install Python 3.8, possibly in a virtualenv.

  2. Download the Google App Engine SDK (GAE) for Python and follow the installation instructions.

  3. git clone https://github.com/mideind/Netskrafl to your GAE application directory.

  4. Run pip install -r requirements.txt in your virtualenv to install required Python packages so that they are accessible to GAE.

  5. Run python dawgbuilder.py to generate the DAWG *.bin.dawg files. This may take a couple of minutes.

  6. Create a secret session key for Flask in resources/secret_key.bin (see How to generate good secret keys, you need to scroll down to find the heading).

  7. Install Node.js if you haven't already. Run npm install to install Node dependencies.

  8. In a separate terminal window, but in the Netskrafl directory, run grunt make. Then run grunt to start watching changes of js and css files.

  9. Run either runserver.bat or runserver.sh.

Or, alternatively:

Run ./setup-dev.sh (tested on Debian based Linux and OS X).

Generating a new vocabulary file

To generate a new vocabulary file (ordalisti.full.sorted.txt), assuming you already have the BÍN database in PostgreSQL (here in table sigrunarsnid - remember to use the is_IS collation locale!), invoke psql, log in to your database and create the following view:

create or replace view skrafl as
   select stofn, utg, ordfl, fl, ordmynd, beyging from sigrunarsnid
   where ordmynd ~ '^[aábdðeéfghiíjklmnoóprstuúvxyýþæö]{3,15}$'
   and fl <> 'bibl'
   and not ((beyging like 'SP-%-FT') or (beyging like 'SP-%-FT2'))
   order by ordmynd;

To explain, this extracts all 3-15 letter word forms containing only Icelandic lowercase alphabetic characters, omitting the bibl (Biblical) category (which contains mostly obscure proper names and derivations thereof), and also omitting plural question forms (spurnarmyndir í fleirtölu).

Then, to generate the vocabulary file from the psql command line:

\copy (select distinct ordmynd from skrafl) to '/home/username/github/Netskrafl/resources/ordalisti.full.sorted.txt';

To extract only the subset of BÍN used by the robot Miðlungur, use the following view, assuming you have the Kristínarsnið form of BÍN in the table kristinarsnid containing the malsnid and einkunn columns:

create or replace view skrafl_midlungur as
	select stofn, utg, ordfl, fl, ordmynd, beyging
	from kristinarsnid
	where (malsnid is null or (malsnid <> ALL (ARRAY['SKALD', 'FORN', 'URE', 'STAD'])))
		and einkunn > 0;

You can then use the skrafl_midlungur view as the underlying table for the previous (vocabulary) query, replacing sigrunarsnid with skrafl_midlungur.

Original Author

Vilhjálmur Þorsteinsson, Reykjavík, Iceland.

Contact me via GitHub for queries or information regarding Netskrafl.

Please contact me if you have plans for using Netskrafl as a basis for your own game website and prefer not to operate under the conditions of the CC-BY-NC 4.0 license (see below).

License

Netskrafl - an Icelandic crossword game website

Copyright © 2021 Miðeind ehf.

This set of programs is licensed under the Creative Commons Attribution-NonCommercial 4.0 International Public License (CC-BY-NC 4.0).

The full text of the license is available here: https://creativecommons.org/licenses/by-nc/4.0/legalcode.

Included third party software

Netskrafl contains the DragDropTouch.js module by Bernardo Castilho, which is licensed under the MIT license as follows:

Copyright © 2016 Bernardo Castilho

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

Netskrafl contains the jQuery UI Touch Punch library by David Furfero, which is licensed under the MIT license.

Copyright © 2011 David Furfero

The MIT license, as spelled out above, applies to this library.

Trademarks

SCRABBLE is a registered trademark. This software or its author are in no way affiliated with or endorsed by the owners or licensees of the SCRABBLE trademark.