Well I was thinking of them using the underhive assets because they're already there. And now you've got me thinking about it so here. Classic zerg mode of 2 camps underground with some sort of objective between them. Tyranids spawn in huge waves from this objective, to which each team needs to survive. You can risk trying to kill the other team, but if your "nexus" or whatever is killed by the Tyranid warrior, your team loses the abilty to respawn. First team to lose everyone after their "nexus" is destroyed on their team goes extinct and loses. Between waves, teams have 2-3 minutes to try and take the "flag" objective in the middle of the map and bring it back to their base. This heals their "nexus", restocks ammo crates, lives, w.e. After 2 minutes the harbringers of the next wave start appearing. Light annoyances of several guants getting in the way. At the 3 minute mark, the next wave has arrived and teams will have to do almost everything they can just to survive after several waves. If it's possible to put more than 10 people on a single team, this would be utterly epic. Because it would mean even if the Tyranid horde eas bearing down on the camp, a few people could try to navigate their way through the areas of the map with the least interference from the tyranids on an attempt to sabotage the other teams chances of survival (overwhelm the ability of the other side to fight off the Tyranids against their "nexus"). There's tons of other things they could do here, like adding secondary objectives like spawning pools/eggs that summon more warriors, so the periods between waves will force players to evaluate a few different options at once: restock/repair the base by grabbing the central objective? Clear the warrior spawns on your side of the map? Assault their base directly in attempt to put minor damage to their nexus?