backwards: Add games module

hosts/backwards/modules/games/default.nix

@@ -0,0 +1,13 @@
+{ pkgs, ... }:
+{
+  home-manager.users.alex = {
+    home.packages = [
+      (pkgs.retroarch.override {
+        cores = [
+          pkgs.libretro.snes9x
+          pkgs.libretro.genesis-plus-gx
+        ];
+      })
+    ];
+  };
+}