diff --git a/data/hu.kramo.Cartridges.gschema.xml b/data/hu.kramo.Cartridges.gschema.xml
index f4a9368..1230c42 100644
--- a/data/hu.kramo.Cartridges.gschema.xml
+++ b/data/hu.kramo.Cartridges.gschema.xml
@@ -16,6 +16,12 @@
     <key name="steam-location" type="s">
       <default>"~/.steam/"</default>
     </key>
+    <key name="steam-flatpak-location" type="s">
+      <default>~/.var/app/com.valvesoftware.Steam/data/Steam/</default>
+    </key>
+    <key name="steam-windows-location" type="s">
+      <default>"C:\Program Files (x86)\Steam"</default>
+    </key>
     <key name="lutris" type="b">
       <default>true</default>
     </key>
diff --git a/src/importer/importer.py b/src/importer/importer.py
index 42aac19..2f1e5ae 100644
--- a/src/importer/importer.py
+++ b/src/importer/importer.py
@@ -116,6 +116,8 @@ class Importer:
                     exc_info=exception,
                 )
                 continue
+            if game is None:
+                continue
 
             # TODO register in store instead of dict
 
diff --git a/src/importer/source.py b/src/importer/source.py
index a2fca0c..663b92e 100644
--- a/src/importer/source.py
+++ b/src/importer/source.py
@@ -1,35 +1,38 @@
 from abc import abstractmethod
 from collections.abc import Iterable, Iterator, Sized
 
+from src.game import Game
+from src.window import CartridgesWindow
+
 
 class SourceIterator(Iterator, Sized):
     """Data producer for a source of games"""
 
-    source = None
+    source: "Source" = None
 
-    def __init__(self, source) -> None:
+    def __init__(self, source: "Source") -> None:
         super().__init__()
         self.source = source
 
-    def __iter__(self):
+    def __iter__(self) -> "SourceIterator":
         return self
 
     @abstractmethod
-    def __len__(self):
+    def __len__(self) -> int:
         """Get a rough estimate of the number of games produced by the source"""
 
     @abstractmethod
-    def __next__(self):
+    def __next__(self) -> "Game" | None:
         """Get the next generated game from the source.
         Raises StopIteration when exhausted.
-        May raise any other exception signifying an error on this specific game."""
+        May raise any other exception signifying an error on this specific game.
+        May return None when a game has been skipped without an error."""
 
 
 class Source(Iterable):
     """Source of games. E.g an installed app with a config file that lists game directories"""
 
-    win = None
-
+    win: "CartridgesWindow" = None
     name: str
     variant: str
 
@@ -38,7 +41,7 @@ class Source(Iterable):
         self.win = win
 
     @property
-    def full_name(self):
+    def full_name(self) -> str:
         """The source's full name"""
         full_name_ = self.name
         if self.variant is not None:
@@ -46,7 +49,7 @@ class Source(Iterable):
         return full_name_
 
     @property
-    def id(self):  # pylint: disable=invalid-name
+    def id(self) -> str:  # pylint: disable=invalid-name
         """The source's identifier"""
         id_ = self.name.lower()
         if self.variant is not None:
@@ -54,7 +57,7 @@ class Source(Iterable):
         return id_
 
     @property
-    def game_id_format(self):
+    def game_id_format(self) -> str:
         """The string format used to construct game IDs"""
         format_ = self.name.lower()
         if self.variant is not None:
@@ -64,14 +67,14 @@ class Source(Iterable):
 
     @property
     @abstractmethod
-    def executable_format(self):
+    def executable_format(self) -> str:
         """The executable format used to construct game executables"""
 
     @property
     @abstractmethod
-    def is_installed(self):
+    def is_installed(self) -> bool:
         """Whether the source is detected as installed"""
 
     @abstractmethod
-    def __iter__(self):
+    def __iter__(self) -> SourceIterator:
         """Get the source's iterator, to use in for loops"""
diff --git a/src/importer/sources/steam_source.py b/src/importer/sources/steam_source.py
new file mode 100644
index 0000000..d548009
--- /dev/null
+++ b/src/importer/sources/steam_source.py
@@ -0,0 +1,180 @@
+import re
+import logging
+from time import time
+from pathlib import Path
+
+import requests
+from requests import HTTPError, JSONDecodeError
+
+from src.game import Game
+from src.importer.source import Source, SourceIterator
+from src.utils.decorators import (
+    replaced_by_path,
+    replaced_by_schema_key,
+    replaced_by_env_path,
+)
+from src.utils.save_cover import resize_cover, save_cover
+
+
+class SteamAPIError(Exception):
+    pass
+
+
+class SteamSourceIterator(SourceIterator):
+    source: "SteamSource"
+
+    manifests = None
+    manifests_iterator = None
+
+    installed_state_mask = 4
+
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+
+        self.manifests = set()
+
+        # Get dirs that contain steam app manifests
+        manifests_dirs = set()
+        libraryfolders_path = self.source.location / "steamapps" / "libraryfolders.vdf"
+        with open(libraryfolders_path, "r") as file:
+            for line in file.readlines():
+                line = line.strip()
+                prefix = '"path"'
+                if not line.startswith(prefix):
+                    continue
+                library_folder = Path(line[len(prefix) :].strip()[1:-1])
+                manifests_dir = library_folder / "steamapps"
+                if not (manifests_dir).is_dir():
+                    continue
+                manifests_dirs.add(manifests_dir)
+
+        # Get app manifests
+        for manifests_dir in manifests_dirs:
+            for child in manifests_dir.iterdir():
+                if child.is_file() and "appmanifest" in child.name:
+                    self.manifests.add(child)
+
+        self.manifests_iterator = iter(self.manifests)
+
+    def __len__(self):
+        return len(self.manifests)
+
+    def __next__(self):
+        # Get metadata from manifest
+        # Ignore manifests that don't have a value for all keys
+        manifest = next(self.manifests_iterator)
+        manifest_data = {"name": None, "appid": None, "StateFlags": "0"}
+        try:
+            with open(manifest) as file:
+                contents = file.read()
+                for key in manifest_data:
+                    regex = f'"{key}"\s+"(.*)"\n'
+                    if (match := re.search(regex, contents)) is None:
+                        return None
+                    manifest_data[key] = match.group(1)
+        except OSError:
+            return None
+
+        # Skip non installed games
+        if not int(manifest_data["StateFlags"]) & self.installed_state_mask:
+            return None
+
+        # Build basic game
+        appid = manifest_data["appid"]
+        values = {
+            "added": int(time()),
+            "name": manifest_data["name"],
+            "hidden": False,
+            "source": self.source.id,
+            "game_id": self.source.game_id_format.format(game_id=appid),
+            "executable": self.source.executable_format.format(game_id=appid),
+            "blacklisted": False,
+            "developer": None,
+        }
+        game = Game(self.source.win, values, allow_side_effects=False)
+
+        # Add official cover image
+        cover_path = (
+            self.source.location
+            / "appcache"
+            / "librarycache"
+            / f"{appid}_library_600x900.jpg"
+        )
+        if cover_path.is_file():
+            save_cover(self.win, game.game_id, resize_cover(self.win, cover_path))
+
+        # Make Steam API call
+        try:
+            with requests.get(
+                "https://store.steampowered.com/api/appdetails?appids=%s"
+                % manifest_data["appid"],
+                timeout=5,
+            ) as response:
+                response.raise_for_status()
+                steam_api_data = response.json()[appid]
+        except (HTTPError, JSONDecodeError) as error:
+            logging.warning(
+                "Error while querying Steam API for %s (%s)",
+                manifest_data["name"],
+                manifest_data["appid"],
+                exc_info=error,
+            )
+            return game
+
+        # Fill out new values
+        if not steam_api_data["success"] or steam_api_data["data"]["type"] != "game":
+            values["blacklisted"] = True
+        else:
+            values["developer"] = ", ".join(steam_api_data["data"]["developers"])
+        game.update_values(values)
+        return game
+
+
+class SteamSource(Source):
+    name = "Steam"
+    executable_format = "xdg-open steam://rungameid/{game_id}"
+    location = None
+
+    @property
+    def is_installed(self):
+        # pylint: disable=pointless-statement
+        try:
+            self.location
+        except FileNotFoundError:
+            return False
+        return True
+
+    def __iter__(self):
+        return SteamSourceIterator(source=self)
+
+
+class SteamNativeSource(SteamSource):
+    variant = "native"
+
+    @property
+    @replaced_by_schema_key("steam-location")
+    @replaced_by_env_path("XDG_DATA_HOME", "Steam/")
+    @replaced_by_path("~/.steam/")
+    @replaced_by_path("~/.local/share/Steam/")
+    def location(self):
+        raise FileNotFoundError()
+
+
+class SteamFlatpakSource(SteamSource):
+    variant = "flatpak"
+
+    @property
+    @replaced_by_schema_key("steam-flatpak-location")
+    @replaced_by_path("~/.var/app/com.valvesoftware.Steam/data/Steam/")
+    def location(self):
+        raise FileNotFoundError()
+
+
+class SteamWindowsSource(SteamSource):
+    variant = "windows"
+
+    @property
+    @replaced_by_schema_key("steam-windows-location")
+    @replaced_by_env_path("programfiles(x86)", "Steam")
+    def location(self):
+        raise FileNotFoundError()
diff --git a/src/main.py b/src/main.py
index 37ffe9a..9d3a3b8 100644
--- a/src/main.py
+++ b/src/main.py
@@ -36,6 +36,11 @@ from src.importer.sources.lutris_source import (
     LutrisFlatpakSource,
     LutrisNativeSource,
 )
+from src.importer.sources.steam_source import (
+    SteamNativeSource,
+    SteamFlatpakSource,
+    SteamWindowsSource,
+)
 from src.preferences import PreferencesWindow
 from src.window import CartridgesWindow
 
@@ -156,6 +161,10 @@ class CartridgesApplication(Adw.Application):
         if self.win.schema.get_boolean("lutris"):
             importer.add_source(LutrisNativeSource(self.win))
             importer.add_source(LutrisFlatpakSource(self.win))
+        if self.win.schema.get_boolean("steam"):
+            importer.add_source(SteamNativeSource(self.win))
+            importer.add_source(SteamFlatpakSource(self.win))
+            importer.add_source(SteamWindowsSource(self.win))
         importer.run()
 
     def on_remove_game_action(self, *_args):
diff --git a/src/utils/decorators.py b/src/utils/decorators.py
index 0ec1ea7..456c450 100644
--- a/src/utils/decorators.py
+++ b/src/utils/decorators.py
@@ -14,7 +14,7 @@ class MyClass():
 """
 
 from pathlib import Path
-from os import PathLike
+from os import PathLike, environ
 from functools import wraps
 
 
@@ -52,3 +52,21 @@ def replaced_by_schema_key(key: str):  # Decorator builder
         return wrapper
 
     return decorator
+
+
+def replaced_by_env_path(env_var_name: str, suffix: PathLike | None = None):
+    """Replace the method's returned path with a path whose root is the env variable"""
+
+    def decorator(original_function):  # Built decorator (closure)
+        @wraps(original_function)
+        def wrapper(*args, **kwargs):  # func's override
+            try:
+                env_var = environ[env_var_name]
+            except KeyError:
+                return original_function(*args, **kwargs)
+            override = Path(env_var) / suffix
+            return replaced_by_path(override)(original_function)(*args, **kwargs)
+
+        return wrapper
+
+    return decorator