chore(aspen/system): Don't install xonotic on every system

Change-Id: I664f97b2321625482ef64218b51c93ba28599643
Reviewed-on: https://cl.tvl.fyi/c/depot/+/11309
Autosubmit: aspen <root@gws.fyi>
Reviewed-by: aspen <root@gws.fyi>
Tested-by: BuildkiteCI

users/aspen/system/home/modules/games.nix

@@ -46,16 +46,6 @@ let
 
 in
 mkMerge [
-  {
+  { home.packages = [ crawl ]; }
-    home.packages = [
+  (mkIf stdenv.isLinux { home.packages = [ df prismlauncher ]; })
-      crawl
-      xonotic
-    ];
-  }
-  (mkIf stdenv.isLinux {
-    home.packages = [
-      df
-      prismlauncher
-    ];
-  })
 ]