If you would somehow buff the Quake1 engine by grafting every single improvement from both official addons and all signigficant mods (i.e. custom functions and entities like rotating brushes or breakables that can be set to vanish only by explosives) onto the vanilla Q1's source code itself, is there still some noteworthy feature left-out that can only done be in Quake2's engine or Goldsrc?