diff --git a/lua/plugins/debugger.lua b/lua/plugins/debugger.lua
index 4066670..5bfd5e3 100644
--- a/lua/plugins/debugger.lua
+++ b/lua/plugins/debugger.lua
@@ -268,6 +268,62 @@ return {
         end
 
         dap.configurations.c = dap.configurations.cpp
+
+        -- Unity (Mono soft debugger) via Unity's MIT-licensed vscode-unity-debug
+        -- adapter, extracted from its .vsix into stdpath("data")/unity-debug.
+        -- Avoids vstuc, whose license (like vsdbg's) is VS Code only.
+        --
+        -- UnityDebug.exe is patched by unity-debug/install.sh (see patch.cs there;
+        -- original kept as UnityDebug.exe.orig): stock, it only matches editor
+        -- processes named exactly "Unity"/"Unity Editor", but Unity Hub launches
+        -- the editor as "unityhub-unity-editor-<version>". The patch makes it a
+        -- case-insensitive "Unity" prefix match, covering both launch methods and
+        -- any version. Helper processes (UnityPackageManager, import workers...)
+        -- match too, so the adapter picks the real editor by the process_id in
+        -- EditorInstance.json -- which needs the config name to contain "Editor".
+        local unity_debug_exe = vim.fn.stdpath("data") .. "/unity-debug/extension/bin/UnityDebug.exe"
+        local unity_debug_install = vim.fn.stdpath("config") .. "/unity-debug/install.sh"
+        dap.adapters.unity = function(callback)
+            if vim.fn.filereadable(unity_debug_exe) == 0 then
+                vim.notify("Installing Unity debug adapter...")
+                local result = vim.system({ unity_debug_install }, { text = true }):wait()
+                if result.code ~= 0 then
+                    vim.notify("Unity debug adapter install failed:\n" .. result.stderr, vim.log.levels.ERROR)
+                    return
+                end
+            end
+            callback({
+                type = "executable",
+                command = "mono",
+                args = { unity_debug_exe },
+                -- The adapter strips the leading "/" from `path` (a Windows-ism)
+                -- before reading it, so run it from / for the now-relative path
+                -- to resolve.
+                options = { cwd = "/" },
+            })
+        end
+
+        -- Library/EditorInstance.json only exists while the editor is open; the
+        -- adapter reads the editor PID from it to derive the debugger port.
+        -- The Unity project may sit in a repo subfolder, so search upward from
+        -- the buffer first, then downward from cwd.
+        local function unity_editor_instance()
+            local root = vim.fs.root(0, "ProjectSettings")
+            if root then
+                return root .. "/Library/EditorInstance.json"
+            end
+            local found = vim.fs.find("EditorInstance.json", { path = vim.fn.getcwd(), type = "file", limit = 1 })
+            return found[1]
+        end
+
+        dap.configurations.cs = {
+            {
+                name = "Unity Editor",
+                type = "unity",
+                request = "launch", -- unity-debug attaches to the running editor despite "launch"
+                path = unity_editor_instance,
+            },
+        }
     end
 }
 
diff --git a/unity-debug/install.sh b/unity-debug/install.sh
new file mode 100755
index 0000000..ff9bcb4
--- /dev/null
+++ b/unity-debug/install.sh
@@ -0,0 +1,29 @@
+#!/usr/bin/env bash
+# Installs Unity's MIT-licensed vscode-unity-debug adapter for nvim-dap and
+# patches it to find editors however they were launched (see patch.cs).
+# Re-runnable: always re-extracts and re-patches from the pristine .vsix.
+set -euo pipefail
+
+VERSION=3.0.1
+HERE="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+DEST="${1:-${XDG_DATA_HOME:-$HOME/.local/share}/nvim/unity-debug}"
+BIN="$DEST/extension/bin"
+
+for cmd in curl unzip mono mcs; do
+    command -v "$cmd" >/dev/null || { echo "unity-debug install: missing '$cmd'" >&2; exit 1; }
+done
+
+mkdir -p "$DEST"
+VSIX="$DEST/unity-debug-$VERSION.vsix"
+[ -f "$VSIX" ] || curl -fsSL -o "$VSIX" \
+    "https://github.com/Unity-Technologies/vscode-unity-debug/releases/download/Version-$VERSION/unity-debug-$VERSION.vsix"
+rm -rf "$DEST/extension"
+unzip -qo "$VSIX" -d "$DEST"
+
+TMP="$(mktemp -d)"
+trap 'rm -rf "$TMP"' EXIT
+mcs "$HERE/patch.cs" -r:"$BIN/Mono.Cecil.dll" -out:"$TMP/patch.exe"
+cp "$BIN/UnityDebug.exe" "$BIN/UnityDebug.exe.orig"
+MONO_PATH="$BIN" mono "$TMP/patch.exe" "$BIN/UnityDebug.exe.orig" "$TMP/UnityDebug.exe"
+cp "$TMP/UnityDebug.exe" "$BIN/UnityDebug.exe"
+echo "unity-debug installed and patched in $DEST"
diff --git a/unity-debug/patch.cs b/unity-debug/patch.cs
new file mode 100644
index 0000000..e5a85e3
--- /dev/null
+++ b/unity-debug/patch.cs
@@ -0,0 +1,20 @@
+// Patches vscode-unity-debug's UnityProcessDiscovery.GetUnityEditorProcesses to
+// prefix-match process names instead of requiring an exact "Unity"/"Unity Editor".
+// The comparison is OrdinalIgnoreCase, so the "Unity" prefix then matches editors
+// launched directly ("Unity") and via Unity Hub ("unityhub-unity-editor-<version>").
+// Extra matches (UnityPackageManager etc.) are fine: with a config name containing
+// "Editor", the adapter picks the editor by process_id from EditorInstance.json.
+using System; using System.Linq; using Mono.Cecil;
+class Patch {
+    static int Main(string[] a) {
+        var asm = AssemblyDefinition.ReadAssembly(a[0]);
+        var m = asm.MainModule.Types.SelectMany(t => t.Methods).Single(x => x.Name == "GetUnityEditorProcesses");
+        var startsWith = asm.MainModule.ImportReference(typeof(string).GetMethod("StartsWith", new[] { typeof(string), typeof(StringComparison) }));
+        int c = 0;
+        foreach (var i in m.Body.Instructions)
+            if (i.Operand is MethodReference r && r.DeclaringType.FullName == "System.String" && r.Name == "Equals" && r.Parameters.Count == 2) { i.Operand = startsWith; c++; }
+        if (c != 1) { Console.Error.WriteLine($"expected 1 string.Equals call in {m.Name}, found {c}"); return 1; }
+        asm.Write(a[1]);
+        return 0;
+    }
+}