diff --git a/src/App.zig b/src/App.zig
index ae5db5b..a2b0349 100644
--- a/src/App.zig
+++ b/src/App.zig
@@ -5,24 +5,18 @@ const Bus = @import("nu/Bus.zig");
 const Render = @import("nu/Render.zig");
 const ImGui = @import("nu/ImGui.zig");
 
-pub fn module() nu.Module {
-    return nu.Module{
-        .name = "App",
-        // .dependencies = &.{ Render.module(), ImGui.module() },
-        .setup = setup,
-        .teardown = teardown,
-        .update = update,
-    };
-}
+pub const depends = .{ ImGui, Render };
 
-pub fn setup(_: std.mem.Allocator) !void {
-    try ImGui.gui.register(gui);
-}
+pub fn setup(_: std.mem.Allocator) !void {}
 
 pub fn teardown() void {}
 
 pub fn update() !void {}
 
-pub fn gui() void {
+pub fn frame() !void {
     ImGui.igShowMetricsWindow(null);
 }
+
+// pub fn gui() void {
+//     ImGui.igShowMetricsWindow(null);
+// }
diff --git a/src/main.zig b/src/main.zig
index 6c1751c..92139b5 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -22,8 +22,8 @@ pub const nu_options: nu.Options = .{
 // component of the larger structure.
 
 pub const nu_driver = nu.Window;
+pub const nu_present = nu.Render;
 pub const nu_modules = .{
-    nu.Render,
     nu.ImGui,
     App,
 };
diff --git a/src/nu.zig b/src/nu.zig
index 09a2020..d0df829 100644
--- a/src/nu.zig
+++ b/src/nu.zig
@@ -15,73 +15,90 @@ const Config = struct {
 
 pub const config: Config = if (@hasDecl(root, "nu_config")) root.nu_config else .{};
 
-pub const Module = struct {
-    // todo dependencies
-    name: []const u8,
-    setup: *const fn (alloc: std.mem.Allocator) anyerror!void,
-    teardown: *const fn () void,
-    update: ?*const fn () anyerror!void = null,
-    frame: ?*const fn () anyerror!void = null,
-    dependencies: []const Module = &.{},
-};
-
-pub const Driver = struct {
-    module: Module,
-    next: *const fn () bool, // events? callbacks?
-};
-
-fn enable(modules: *std.StringArrayHashMap(Module), module: Module) void {
-    // this doesn't handle dependencies correctly. need to do real topological sort.
-
-    if (modules.contains(module.name)) return;
-    for (module.dependencies) |dep| enable(modules, dep);
-    modules.putNoClobber(module.name, module) catch @panic("OOM");
-}
-
 pub fn main() void {
     var gpa = std.heap.GeneralPurposeAllocator(.{}){};
     const alloc = gpa.allocator();
 
-    var modules = std.StringArrayHashMap(Module).init(alloc);
-    defer modules.deinit();
+    const engine = Engine(root.nu_driver, root.nu_present, root.nu_modules);
 
-    const driver = root.nu_driver.driver();
-    enable(&modules, driver.module);
-    inline for (root.nu_modules) |mod| {
-        enable(&modules, mod.module());
-    }
+    engine.try_invoke("setup", .{alloc}) catch @panic("Startup failed");
+    defer engine.rinvoke("teardown", .{});
 
-    for (modules.values()) |mod| {
-        std.log.debug("{s}.setup", .{mod.name});
-        mod.setup(alloc) catch |err| {
-            std.debug.panic("Module {s} setup error: {!}", .{ mod.name, err });
-        };
-    }
-    defer {
-        var rev = std.mem.reverseIterator(modules.values());
-        while (rev.next()) |mod| {
-            std.log.debug("{s}.teardown", .{mod.name});
-            mod.teardown();
-        }
-    }
+    while (engine.next()) {
+        engine.try_invoke("fixed", .{}) catch @panic("fixed failed!");
+        engine.try_invoke("frame", .{}) catch @panic("frame failed!");
 
-    std.log.info("Loaded modules: {s}", .{modules.keys()});
-
-    while (driver.next()) {
-        for (modules.values()) |mod| {
-            if (mod.update) |update| {
-                update() catch |err| {
-                    std.debug.panic("Module {s} update event error: {!}", .{ mod.name, err });
-                };
-            }
-        }
-
-        for (modules.values()) |mod| {
-            if (mod.frame) |frame| {
-                frame() catch |err| {
-                    std.debug.panic("Module {s} frame event error: {!}", .{ mod.name, err });
-                };
-            }
-        }
+        engine.render() catch @panic("render failed!");
     }
 }
+
+pub fn Engine(comptime D: type, comptime R: type, comptime M: anytype) type {
+    return struct {
+        pub const modules = Graph.sort(.{ D, R } ++ M);
+
+        pub fn next() bool {
+            return D.next();
+        }
+
+        pub fn render() !void {
+            return R.render(@This());
+        }
+
+        pub fn try_invoke(comptime name: []const u8, args: anytype) !void {
+            inline for (modules) |mod| {
+                if (@hasDecl(mod, name)) {
+                    try @call(.auto, @field(mod, name), args);
+                }
+            }
+        }
+
+        pub fn invoke(comptime name: []const u8, args: anytype) void {
+            inline for (modules) |mod| {
+                if (@hasDecl(mod, name)) {
+                    @call(.auto, @field(mod, name), args);
+                }
+            }
+        }
+
+        pub fn try_rinvoke(comptime name: []const u8, args: anytype) !void {
+            comptime var it = std.mem.reverseIterator(modules);
+            inline while (it.next()) |mod| {
+                if (@hasDecl(mod, name)) {
+                    try @call(.auto, @field(mod, name), args);
+                }
+            }
+        }
+
+        pub fn rinvoke(comptime name: []const u8, args: anytype) void {
+            comptime var it = std.mem.reverseIterator(modules);
+            inline while (it.next()) |mod| {
+                if (@hasDecl(mod, name)) {
+                    @call(.auto, @field(mod, name), args);
+                }
+            }
+        }
+    };
+}
+
+const Graph = struct {
+    fn visit(
+        comptime mod: type,
+        comptime mark: *[]const type,
+        comptime result: *[]const type,
+    ) void {
+        if (std.mem.indexOfScalar(type, result.*, mod)) |_| return;
+        if (std.mem.indexOfScalar(type, mark.*, mod)) |_| @compileError("Cycle");
+        mark.* = mark.* ++ .{mod};
+        if (@hasDecl(mod, "depends"))
+            for (mod.depends) |dep|
+                visit(dep, mark, result);
+        result.* = result.* ++ .{mod};
+    }
+
+    fn sort(comptime modules: anytype) []const type {
+        var mark: []const type = &.{};
+        var result: []const type = &.{};
+        for (modules) |mod| visit(mod, &mark, &result);
+        return result;
+    }
+};
diff --git a/src/nu/ImGui.zig b/src/nu/ImGui.zig
index d96a0de..a65b513 100644
--- a/src/nu/ImGui.zig
+++ b/src/nu/ImGui.zig
@@ -16,29 +16,17 @@ pub usingnamespace im;
 pub const Config = struct {};
 const config = nu.config.imgui;
 
-pub fn module() nu.Module {
-    return nu.Module{
-        .name = "ImGui",
-        // .dependencies = &.{Render.module()},
-        .setup = setup,
-        .teardown = teardown,
-        .update = update,
-    };
-}
+pub const depends = .{ Render, Window };
 
 pub fn loader_wrapper(procname: [*c]const u8, _: ?*anyopaque) callconv(.C) vk.PfnVoidFunction {
     return au.glfwGetInstanceProcAddress(au.I.handle, procname);
 }
 
-pub var gui: Hook(fn () void) = undefined;
 var ctx: *im.ImGuiContext = undefined;
 var descriptor_pool: vk.DescriptorPool = undefined;
 
-pub fn setup(alloc: std.mem.Allocator) !void {
-    gui = @TypeOf(gui).init(alloc);
-    errdefer gui.deinit();
-
-    try Render.present.register(present);
+pub fn setup(_: std.mem.Allocator) !void {
+    // try Render.present.register(present);
 
     ctx = im.igCreateContext(null) orelse {
         return error.igCreateContextFailed;
@@ -104,21 +92,18 @@ pub fn teardown() void {
     au.D.destroyDescriptorPool(descriptor_pool, null);
     im.impl.ImGui_ImplGlfw_Shutdown();
     im.igDestroyContext(ctx);
-    gui.deinit();
 }
 
-pub fn update() !void {
+pub fn frame() !void {
     im.impl.ImGui_ImplGlfw_NewFrame();
     im.impl.ImGui_ImplVulkan_NewFrame();
     im.igNewFrame();
-
-    gui.invoke(.{});
-
-    im.igEndFrame();
-    im.igRender();
 }
 
 pub fn present(cmd: au.CommandBufferProxy) void {
+    im.igEndFrame();
+    im.igRender();
+
     im.impl.ImGui_ImplVulkan_RenderDrawData(
         @ptrCast(im.igGetDrawData()),
         @ptrFromInt(@intFromEnum(cmd.handle)),
diff --git a/src/nu/Render.zig b/src/nu/Render.zig
index 3e4ddac..3a6694f 100644
--- a/src/nu/Render.zig
+++ b/src/nu/Render.zig
@@ -32,21 +32,11 @@ pub const Config = struct {
 };
 const config = nu.config.render;
 
-pub fn module() nu.Module {
-    return nu.Module{
-        .name = "Render",
-        .setup = setup,
-        .teardown = teardown,
-        .frame = frame,
-        .dependencies = &.{nu.Window.driver().module},
-    };
-}
+pub const depends = .{nu.Window};
 
 var sc: au.SwapChain = undefined;
 var flights: au.Flights = undefined;
 
-pub var present: nu.Hook(fn (au.CommandBufferProxy) void) = undefined;
-
 pub fn setup(alloc: std.mem.Allocator) !void {
     // todo pick apart au into helpers; not a sub-module filled with its own globals.
     try au.init(alloc);
@@ -57,20 +47,16 @@ pub fn setup(alloc: std.mem.Allocator) !void {
 
     flights = try au.Flights.init(alloc, config.frames_in_flight);
     errdefer flights.deinit();
-
-    present = @TypeOf(present).init(alloc);
-    errdefer present.deinit();
 }
 
 pub fn teardown() void {
     au.D.deviceWaitIdle() catch |err| std.debug.panic("Device wait failed: {!}", .{err});
-    errdefer present.deinit();
     flights.deinit();
     sc.deinit();
     au.deinit();
 }
 
-pub fn frame() !void {
+pub fn render(engine: anytype) !void {
     const flight: au.Flights.Flight = flights.next();
     try flight.wait();
 
@@ -97,9 +83,8 @@ pub fn frame() !void {
         target.begin_rendering(cmd, render_area);
 
         // todo manage frame in flight state for each hook; pass the current flight in as context.
-        // will need some comptime -> anytype mapping.
 
-        present.invoke(.{cmd});
+        engine.invoke("present", .{cmd});
 
         target.end_rendering(cmd);
         try cmd.endCommandBuffer();