How about adding some skulls to custom games? Not all skulls, though most though. Examples of skulls that work for custom games are mythic, boom, foreign (If Elites come back), famine, (Bandanna/optional), fog, malfunction, recession, black eye, eye patch, piñata, grunt birthday (headshots but for spartans or elites instead of grunts), grunt funeral (instead all of your grenades explode when you die or someone dies).
Remember: The skull’s effects apply to all players in custom games.
(I’ve had this idea for a while but forgot to post it.) Please like or comment on what you think about having skull in custom games.