diff --git a/README.md b/README.md
index 8a3e269..ec08451 100644
--- a/README.md
+++ b/README.md
@@ -1 +1,100 @@
-# unity-action
\ No newline at end of file
+# setup-unity
+
+<p align="left">
+  <a href="https://github.com/kuler90/setup-unity/actions"><img alt="GitHub Actions status" src="https://github.com/kuler90/setup-unity/workflows/test/badge.svg"></a>
+</p>
+
+GitHub Action to download and install Unity. Based on Unity Hub.
+
+Works on Ubuntu, macOS and Windows.
+
+## Inputs
+
+### `unity-version`
+
+Unity version to install. For example, `2019.4.9f1`. Project version will be used if not provided.
+
+### `unity-version-changeset`
+
+Unity version changeset. For example, `50fe8a171dd9`. Automatically parsed from Unity site if not provided.
+
+### `unity-modules`
+
+List of Unity modules (e.g. build support) to install. For example, `[ios, android, webgl]`.
+
+Available modules:
+
+    Documentation: documentation
+    Standard Assets: standardassets
+    Example Project: example
+    Android Build Support: android
+    iOS Build Support: ios
+    tvOS Build Support: appletv
+    Linux Build Support: linux-mono
+    SamsungTV Build Support: samsung
+    Tizen Build Support: tizen
+    WebGL Build Support: webgl
+    Windows Build Support: windows
+    Facebook Gameroom Build Support: facebook-games
+    MonoDevelop / Unity Debugger: monodevelop
+    Vuforia Augmented Reality Support: vuforia-ar
+    Language packs: language-ja, language-ko, language-zh-cn, language-zh-hant, language-zh-hans
+    Mac Build Support (IL2CPP): mac-il2cpp
+    Windows Build Support (Mono): windows-mono
+    Android SDK & NDK Tools: android-sdk-ndk-tools
+    OpenJDK: android-open-jdk
+    Lumin OS (Magic Leap) Build Support: lumin
+
+Also list of available modules can be checked by execute: `<path-to-unity-hub> -- --headless help`.
+
+### `unity-modules-child`
+
+Automatically installs all child modules of selected modules. For example, `android-open-jdk` and `android-sdk-ndk-tools` for android. Default `true`.
+
+### `project-path`
+
+Path to Unity project. Used to find Unity version. Default `${{ github.workspace }}`.
+
+### `install-path`
+
+Path where the Unity editor will be installed.
+
+## Outputs
+
+### `unity-version`
+
+Unity version.
+
+### `unity-path`
+
+Unity executable path. Also setted env `UNITY_PATH`.
+
+## Known issues
+
+ - Installing `android` module with childs modules may freeze on macOS.
+ - Workflow may fail with `System.IO.IOException: No space left on device` on GitHub-hosted Ubuntu. Setting `install-path: /mnt` can fix the problem.
+
+## Example usage
+
+```yaml
+- name: Checkout project
+  uses: actions/checkout@v2
+
+- name: Setup Unity
+  uses: kuler90/setup-unity@v1
+  with:
+    unity-modules: android
+
+- name: Activate Unity
+  uses: kuler90/activate-unity@v1
+  with:
+    unity-username: ${{ secrets.UNITY_USERNAME }}
+    unity-password: ${{ secrets.UNITY_PASSWORD }}
+    unity-serial: ${{ secrets.UNITY_SERIAL }}
+
+- name: Build Unity
+  uses: kuler90/build-unity@v1
+  with:
+    build-target: Android
+    build-path: ./build.apk
+```
\ No newline at end of file