#game #weasel #turn-based


A customizable battle system for turn-based games

8 releases (5 breaking)

✓ Uses Rust 2018 edition

0.6.0 Mar 11, 2020
0.5.0 Feb 26, 2020
0.4.1 Feb 22, 2020
0.3.1 Feb 17, 2020
0.1.0 Feb 8, 2020

#79 in Games

Download history 15/week @ 2020-02-07 55/week @ 2020-02-14 65/week @ 2020-02-21 59/week @ 2020-02-28 27/week @ 2020-03-06 31/week @ 2020-03-13

70 downloads per month

MIT license


Weasel Turn Battle System

Build Status Code Coverage crates.io Released API docs License: MIT

weasel is a customizable battle system for turn-based games.

  • Simple way to define the combat's rules, taking advantage of Rust's strong type system.
  • Battle events are collected into a timeline to support save and restore, replays, and more.
  • Client/server architecture; all battle events are verified by the server.
  • Minimal performance overhead.


use weasel::{Server, battle_rules, rules::empty::*};
use weasel::battle::{Battle, BattleRules};
use weasel::team::CreateTeam;
use weasel::event::EventTrigger;

battle_rules! {}

let battle = Battle::builder(CustomRules::new()).build(); 
let mut server = Server::builder(battle).build();

CreateTeam::trigger(&mut server, 1).fire().unwrap();
assert_eq!(server.battle().entities().teams().count(), 1);

You can find real examples of battle systems made with weasel in examples.

How does it work?

To use this library, you would create instances of its main objects: server and client. You will notice that both of them are parameterized with a BattleRules generic type.
A server is mandatory to manage a game. A server can be also a client. For example, a typical single player game needs only one server.
A client is a participant to a game. It sends commands to a server on behalf of a player. A multiplayer game would have one server and multiple clients.

Once you have instantiated a server and possibly one or more clients, you are ready to begin a new game.
Games are carried forward by creating events. There are many kind of events, see the documentation to know more.

Through a server or a client you'll be able to access the full state of the battle, including the entire timeline of events.


weasel provides many functionalities to ease the development of a turn based game:

  • Creatures and inanimate objects.
  • Statistics and abilities for characters.
  • Long lasting status effects.
  • Player managed teams.
  • Team objectives and diplomacy.
  • Division of the battle into rounds.
  • Rules to govern the game subdivided into orthogonal traits.
  • Fully serializable battle history.
  • Cause-effect relationship between events.
  • Server side verification of clients' events.
  • Player permissions and authorization.
  • Versioning for battle rules.
  • User defined events.
  • System and user defined metrics.
  • Sinks to forward events to an arbitrary destination.
  • Small collection of predefined rules.


Thanks for your interest in contributing! There are many ways to contribute to this project. See CONTRIBUTING.md.


weasel is provided under the MIT license. See LICENSE.


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