diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index d99808e53..325ce30f9 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -1,6 +1,19 @@
 name: Build and Deploy
 on: [push, pull_request, pull_request_target]
 jobs:
+  yamllint:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Checkout
+      uses: actions/checkout@master
+
+    - name: Yamllint
+      uses: ibiqlik/action-yamllint@v3
+      with:
+        file_or_dir: games/*.yaml originals/*.yaml schema/*.yaml
+      env:
+        GITHUB_ACCESS_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
   build-and-deploy:
     runs-on: ubuntu-latest
     steps:
diff --git a/.yamllint.yml b/.yamllint.yml
new file mode 100644
index 000000000..53a03113e
--- /dev/null
+++ b/.yamllint.yml
@@ -0,0 +1,5 @@
+rules:
+  indentation:
+    spaces: 2
+    indent-sequences: false
+    level: warning
diff --git a/games/0.yaml b/games/0.yaml
index bcb6e7c00..d05f1eec7 100644
--- a/games/0.yaml
+++ b/games/0.yaml
@@ -76,9 +76,9 @@
   development: active
   status: playable
   multiplayer:
-    - Competitive
-    - Online
-    - Co-op
+  - Competitive
+  - Online
+  - Co-op
   content: commercial
   langs:
   - Java
diff --git a/games/m.yaml b/games/m.yaml
index a1eff0f94..ccc4f2680 100644
--- a/games/m.yaml
+++ b/games/m.yaml
@@ -496,9 +496,9 @@
   info: A sandbox tower defense game
   updated: 2020-12-23
   images:
-   - https://mindustrygame.github.io/images/1.png
-   - https://mindustrygame.github.io/images/2.png
-   - https://mindustrygame.github.io/images/3.png
+  - https://mindustrygame.github.io/images/1.png
+  - https://mindustrygame.github.io/images/2.png
+  - https://mindustrygame.github.io/images/3.png
 
 - name: MineClone 2
   development: active
diff --git a/originals/g.yaml b/originals/g.yaml
index 5795e97fa..9badb26f5 100644
--- a/originals/g.yaml
+++ b/originals/g.yaml
@@ -258,11 +258,11 @@
   external:
     wikipedia: Gunpoint (video game)
   meta:
-   genres:
-   - Platform
-   - Puzzle
-   themes:
-   - Sci-Fi
+    genres:
+    - Platform
+    - Puzzle
+    themes:
+    - Sci-Fi
 
 - name: Gwent
   external:
@@ -270,9 +270,9 @@
   platforms:
   - Windows
   meta:
-   genres:
-   - Turn-Based Strategy
-   subgenres:
-   - Board Game
-   themes:
-   - Fantasy
+    genres:
+    - Turn-Based Strategy
+    subgenres:
+    - Board Game
+    themes:
+    - Fantasy
diff --git a/package.json b/package.json
index 375c10f13..51bca57d1 100644
--- a/package.json
+++ b/package.json
@@ -5,4 +5,4 @@
     "linguist-languages": "^7.15.0"
   },
   "dependencies": {}
-}
+}
\ No newline at end of file
diff --git a/poetry.lock b/poetry.lock
index 8e890f762..7cd5d3586 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -67,6 +67,14 @@ python-versions = ">=3.6"
 fast = ["fastnumbers (>=2.0.0)"]
 icu = ["PyICU (>=1.0.0)"]
 
+[[package]]
+name = "pathspec"
+version = "0.9.0"
+description = "Utility library for gitignore style pattern matching of file paths."
+category = "main"
+optional = false
+python-versions = "!=3.0.*,!=3.1.*,!=3.2.*,!=3.3.*,!=3.4.*,>=2.7"
+
 [[package]]
 name = "pykwalify"
 version = "1.8.0"
@@ -173,10 +181,22 @@ category = "main"
 optional = false
 python-versions = ">=3.5"
 
+[[package]]
+name = "yamllint"
+version = "1.27.1"
+description = "A linter for YAML files."
+category = "main"
+optional = false
+python-versions = ">=3.6"
+
+[package.dependencies]
+pathspec = ">=0.5.3"
+pyyaml = "*"
+
 [metadata]
 lock-version = "1.1"
 python-versions = "^3.8"
-content-hash = "1cc411e7d9f5235086c93c64f700669e3a43dffae35a62c5e02250447af10e9b"
+content-hash = "85e6f99250c5d6086591dbf9227bc88143c22e161fb6bc21ad1e79339bb29aba"
 
 [metadata.files]
 click = [
@@ -272,6 +292,7 @@ natsort = [
     {file = "natsort-8.0.0-py3-none-any.whl", hash = "sha256:5f5f4ea471d655b1b1611eef1cf0c6d3397095d2d3a1aab7098d6a50e4c3901a"},
     {file = "natsort-8.0.0.tar.gz", hash = "sha256:a0a4fd71aee20a6d648da61e01180a63f7268e69983d0440bd3ad80ef1ba6981"},
 ]
+pathspec = []
 pykwalify = [
     {file = "pykwalify-1.8.0-py2.py3-none-any.whl", hash = "sha256:731dfa87338cca9f559d1fca2bdea37299116e3139b73f78ca90a543722d6651"},
     {file = "pykwalify-1.8.0.tar.gz", hash = "sha256:796b2ad3ed4cb99b88308b533fb2f559c30fa6efb4fa9fda11347f483d245884"},
@@ -365,3 +386,4 @@ unidecode = [
     {file = "Unidecode-1.3.2-py3-none-any.whl", hash = "sha256:215fe33c9d1c889fa823ccb66df91b02524eb8cc8c9c80f9c5b8129754d27829"},
     {file = "Unidecode-1.3.2.tar.gz", hash = "sha256:669898c1528912bcf07f9819dc60df18d057f7528271e31f8ec28cc88ef27504"},
 ]
+yamllint = []
diff --git a/pyproject.toml b/pyproject.toml
index 3c96fbc48..ff116c695 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -17,6 +17,7 @@ jinja2 = "3.0.3"
 python-slugify = "^5.0.2"
 
 [tool.poetry.dev-dependencies]
+yamllint = "^1.27.1"
 
 [build-system]
 requires = ["poetry-core>=1.0.0"]
diff --git a/schema/originals.yaml b/schema/originals.yaml
index 5880acffb..b80f4b783 100644
--- a/schema/originals.yaml
+++ b/schema/originals.yaml
@@ -23,8 +23,8 @@ sequence:
       platforms:
         type: seq
         sequence:
-           - include: platforms
-             unique: True
+          - include: platforms
+            unique: True
       meta:
         include: meta