I am not a map maker so I do not know how hard it would be to add in these type of weapons or maps but I would like to see a few of these created in the near future.

Weapons:
.Kolibri Pistol from Battlefield 1
.Neegan's barbed bat wonder weapon from TWD
.Nailgun
.Chainsaw Gun from Cod Ghost (laser sight included)
.some others I can't think of at the moment

Maps.
.Market Town from N64 Legend of Zelda Ocarina of Time (With the ghouls as a special round)
.Corpse Party RPG Style Map (With Boss)
.Boos Castle from Super Mario 64
.Airplane Zombies
.Fallout 4 Sanctuary Hills
.Many others