The future of [osu!](https://osu.ppy.sh) and the beginning of an open era! Currently known by and released under the release codename "*lazer*". As in sharper than cutting-edge.
This project is under constant development, but we aim to keep things in a stable state. Users are encouraged to try it out and keep it installed alongside the stable *osu!* client. It will continue to evolve to the point of eventually replacing the existing stable client as an update.
**IMPORTANT:** Gameplay mechanics (and other features which you may have come to know and love) are in a constant state of flux. Game balance and final quality-of-life passes come at the end of development, preceded by experimentation and changes which may potentially **reduce playability or usability**. This is done in order to allow us to move forward as developers and designers more efficiently. If this offends you, please consider sticking to a [stable release](https://osu.ppy.sh/home/download) of osu!. We are not yet open to heated discussion over game mechanics and will not be using github as a forum for such discussions just yet.
We are accepting bug reports (please report with as much detail as possible and follow the existing issue templates). Feature requests are also welcome, but understand that our focus is on completing the game to feature parity before adding new features. A few resources are available as starting points to getting involved and understanding the project:
If you are looking to install or test osu! without setting up a development environment, you can consume our [releases](https://github.com/ppy/osu/releases). You can also generally download a version for your current device from the [osu! site](https://osu.ppy.sh/home/download). Failing that, you may use the links below to download the latest version for your operating system of choice:
- The iOS testflight link may fill up (Apple has a hard limit of 10,000 users). We reset it occasionally when this happens. Please do not ask about this. Check back regularly for link resets or follow [peppy](https://twitter.com/ppy) on twitter for announcements of link resets.
osu! is designed to have extensible modular gameplay modes, called "rulesets". Building one of these allows a developer to harness the power of osu! for their own game style. To get started working on a ruleset, we have some templates available [here](https://github.com/ppy/osu/tree/master/Templates).
When working with the codebase, we recommend using an IDE with intelligent code completion and syntax highlighting, such as the latest version of [Visual Studio](https://visualstudio.microsoft.com/vs/), [JetBrains Rider](https://www.jetbrains.com/rider/), or [Visual Studio Code](https://code.visualstudio.com/) with the [EditorConfig](https://marketplace.visualstudio.com/items?itemName=EditorConfig.EditorConfig) and [C#](https://marketplace.visualstudio.com/items?itemName=ms-dotnettools.csharp) plugin installed.
Build configurations for the recommended IDEs (listed above) are included. You should use the provided Build/Run functionality of your IDE to get things going. When testing or building new components, it's highly encouraged you use the `VisualTests` project/configuration. More information on this is provided [below](#contributing).
- Visual Studio / Rider users should load the project via one of the platform-specific `.slnf` files, rather than the main `.sln`. This will allow access to template run configurations.
If you are not interested in debugging *osu!*, you can add `-c Release` to gain performance. In this case, you must replace `Debug` with `Release` in any commands mentioned in this document.
_Due to a historical feature gap between .NET Core and Xamarin, running `dotnet` CLI from the root directory will not work for most commands. This can be resolved by specifying a target `.csproj` or the helper project at `build/Desktop.proj`. Configurations have been provided to work around this issue for all supported IDEs mentioned above._
Sometimes it may be necessary to cross-test changes in [osu-resources](https://github.com/ppy/osu-resources) or [osu-framework](https://github.com/ppy/osu-framework). This can be quickly achieved using included commands:
Windows:
```ps
UseLocalFramework.ps1
UseLocalResources.ps1
```
macOS / Linux:
```ps
UseLocalFramework.sh
UseLocalResources.sh
```
Note that these commands assume you have the relevant project(s) checked out in adjacent directories:
Before committing your code, please run a code formatter. This can be achieved by running `dotnet format` in the command line, or using the `Format code` command in your IDE.
We have adopted some cross-platform, compiler integrated analyzers. They can provide warnings when you are editing, building inside IDE or from command line, as-if they are provided by the compiler itself.
JetBrains ReSharper InspectCode is also used for wider rule sets. You can run it from PowerShell with `.\InspectCode.ps1`. Alternatively, you can install ReSharper or use Rider to get inline support in your IDE of choice.
When it comes to contributing to the project, the two main things you can do to help out are reporting issues and submitting pull requests. Please refer to the [contributing guidelines](CONTRIBUTING.md) to understand how to help in the most effective way possible.
We love to reward quality contributions. If you have made a large contribution, or are a regular contributor, you are welcome to [submit an expense via opencollective](https://opencollective.com/ppy/expenses/new). If you have any questions, feel free to [reach out to peppy](mailto:pe@ppy.sh) before doing so.
*osu!*'s code and framework are licensed under the [MIT licence](https://opensource.org/licenses/MIT). Please see [the licence file](LICENCE) for more information. [tl;dr](https://tldrlegal.com/license/mit-license) you can do whatever you want as long as you include the original copyright and license notice in any copy of the software/source.
Please note that this *does not cover* the usage of the "osu!" or "ppy" branding in any software, resources, advertising or promotion, as this is protected by trademark law.
Please also note that game resources are covered by a separate licence. Please see the [ppy/osu-resources](https://github.com/ppy/osu-resources) repository for clarifications.
