April Fool’s event is great. Why not make the “defense of the position” a permanent game-mode? Wave gameplay/coop action is very fun. It would a new and different type of gameplay to the game, that fits well with the squad system/AI soldiers. No zombies, of course, just your regular, historical, soviet soldiers. 2 modes could be added:
Single player - it would be offline (like training mode) and wouldn’t award any experience, but one could equip any weapons and even tanks and planes in it.
Co-op - up to 4+ people in a lobby (could be a custom match, or regular mode), fighting successive waves of AI squads. The moment everyone dies and isn’t revived, the game ends.
Just imagine doing this on a map like D-Day (maybe you could even add AI-controlled landing craft ships, while everyone has fun in their MG-42s) or Fortified district. It would be awesome.