add play-opus example

examples/play-opus/main.zig

@@ -0,0 +1,17 @@
+const mach = @import("mach");
+
+// The global list of Mach modules registered for use in our application.
+pub const modules = .{
+    mach.Core,
+    mach.Audio,
+    @import("App.zig"),
+};
+
+// TODO(important): use standard entrypoint instead
+pub fn main() !void {
+    // Initialize mach.Core
+    try mach.core.initModule();
+
+    // Main loop
+    while (try mach.core.tick()) {}
+}