diff --git a/games/game_borderlands1.py b/games/game_borderlands1.py
new file mode 100644
index 0000000..4b90b51
--- /dev/null
+++ b/games/game_borderlands1.py
@@ -0,0 +1,153 @@
+import re
+
+import mobase
+from mobase import FileTreeEntry, IFileTree, ModDataChecker
+
+from ..basic_features import BasicModDataChecker
+from ..basic_game import BasicGame
+
+_extention_pattern = re.compile("\\.(upk|umap|u|int|dll|exe)$", re.I)
+_mapslot_pattern = re.compile("^Mapslot\\d\\d?\\.umap$", re.I)
+
+_mod_dirs = {
+    "Binaries".casefold(): "/",
+    "WillowGame".casefold(): "/",
+    "CookedPC".casefold(): "WillowGame/",
+    "Localization".casefold(): "WillowGame/",
+    "Maps".casefold(): "WillowGame/CookedPC/",
+}
+
+_slots_path = "WillowGame/CookedPC/Maps/MapSlots"
+
+
+def _check_filetree(
+    filetree: IFileTree | FileTreeEntry, recurse: bool
+) -> ModDataChecker.CheckReturn:
+    if filetree.isFile():
+        if _extention_pattern.search(filetree.name()):
+            if _mapslot_pattern.search(filetree.name()):
+                return ModDataChecker.FIXABLE
+            else:
+                return ModDataChecker.INVALID
+    elif recurse and isinstance(filetree, IFileTree):
+        status = ModDataChecker.VALID
+        for child in filetree:
+            child_status = _check_filetree(child, True)
+            if child_status is ModDataChecker.INVALID:
+                return ModDataChecker.INVALID
+            elif child_status is ModDataChecker.FIXABLE:
+                status = ModDataChecker.FIXABLE
+        return status
+
+    return ModDataChecker.VALID
+
+
+def _get_nest(filetree: IFileTree) -> IFileTree | None:
+    children = tuple(filetree)
+    if (
+        len(children) == 1
+        and children[0].isDir()
+        and isinstance(children[0], IFileTree)
+        and _mod_dirs.get(children[0].name().casefold()) is None
+    ):
+        return children[0]
+    return None
+
+
+def _get_slotstree(roottree: IFileTree) -> IFileTree:
+    slotstree: IFileTree | None = roottree.find(_slots_path)  # type: ignore
+    if slotstree is None:
+        slotstree = roottree.addDirectory(_slots_path)
+    return slotstree
+
+
+def _fix_mapslots(filetree: IFileTree, roottree: IFileTree) -> None:
+    for child in filetree:
+        if child.isDir() and isinstance(child, IFileTree):
+            _fix_mapslots(child, roottree)
+        elif _mapslot_pattern.search(child.name()):
+            child.moveTo(_get_slotstree(roottree))
+
+
+class Borderlands1ModDataChecker(BasicModDataChecker):
+    def dataLooksValid(self, filetree: IFileTree) -> ModDataChecker.CheckReturn:
+        parent = filetree.parent()
+        if parent is not None:
+            return self.dataLooksValid(parent)
+
+        status = ModDataChecker.VALID
+
+        nest = _get_nest(filetree)
+        if nest is not None:
+            status = ModDataChecker.FIXABLE
+            filetree = nest
+
+        if _check_filetree(filetree, False) is ModDataChecker.INVALID:
+            return ModDataChecker.INVALID
+
+        slotstree = filetree.find(_slots_path)
+        if slotstree is not None and not slotstree.isDir():
+            return ModDataChecker.INVALID
+
+        for child in filetree:
+            if child.isDir():
+                destination = _mod_dirs.get(child.name().casefold())
+                if destination is None:
+                    child_status = _check_filetree(child, True)
+                    if child_status is ModDataChecker.INVALID:
+                        return ModDataChecker.INVALID
+                    elif child_status is ModDataChecker.FIXABLE:
+                        status = ModDataChecker.FIXABLE
+                elif destination != "/":
+                    status = ModDataChecker.FIXABLE
+            elif _mapslot_pattern.search(child.name()):
+                status = ModDataChecker.FIXABLE
+            elif _extention_pattern.search(child.name()):
+                return ModDataChecker.INVALID
+        return status
+
+    def fix(self, filetree: IFileTree) -> IFileTree:
+        nest = _get_nest(filetree)
+        if nest is not None:
+            conflict: FileTreeEntry | None = None
+            for child in tuple(nest):
+                if not child.moveTo(filetree):
+                    conflict = child
+                    conflict.detach()
+            filetree.remove(nest)
+            if conflict is not None:
+                conflict.moveTo(filetree)
+
+        for child in tuple(filetree):
+            if child.isDir() and isinstance(child, IFileTree):
+                destination = _mod_dirs.get(child.name().casefold())
+                if destination is None:
+                    _fix_mapslots(child, filetree)
+                elif destination != "/":
+                    filetree.move(child, destination)
+            elif _mapslot_pattern.search(child.name()):
+                child.moveTo(_get_slotstree(filetree))
+
+        return filetree
+
+
+class Borderlands1Game(BasicGame):
+    Name = "Borderlands 1 Support Plugin"
+    Author = "Miner Of Worlds, RedxYeti, mopioid"
+    Version = "1.0.0"
+
+    def init(self, organizer: mobase.IOrganizer) -> bool:
+        super().init(organizer)
+        self._register_feature(Borderlands1ModDataChecker())
+        return True
+
+    GameName = "Borderlands"
+    GameShortName = "Borderlands"
+    GameNexusName = "Borderlands GOTY"
+    GameSteamId = 8980
+    GameBinary = "Binaries/Borderlands.exe"
+    GameDataPath = "."
+    GameSaveExtension = "sav"
+    GameDocumentsDirectory = "%DOCUMENTS%/My Games/Borderlands/"
+    GameSavesDirectory = "%GAME_DOCUMENTS%/savedata"
+    GameIniFiles = "%GAME_DOCUMENTS%/WillowGame/Config"