Survival: Hospital is the first survival map. This map was added after Trenched was upgraded to Iron Brigade, offering players the chance to test their defensive abilities to the limit. The map is exactly like the original, with Snipe Tuners on the ledges. The difference, in terms of enemies, is that all types - minus those from the Martian Bear add-on - will be attacking, all at rank three(as tough as those in the last five missions of the main game).
One feature is that, every five (5) waves, the player(s) are given a Survival-only special loot, such as Shredder Machine Gun turrets, or the Hyper-Sniper. This can be done a total of ten times, starting after waves five, ten, and so on until wave fifty, in which the bonuses stop.
Another is that, like all survival games out there, the difficulty ramps up per wave, as well as the enemies getting a little bit more health. Even though the game says that there are infinite waves, there are actually one hundred waves, though extremely tough. Players can only be able to push through to said final wave through key turret placement and co-ordination.
Turret placement is one thing that determines on how far you can get. Occasionally, there will be waves with Jacobs and Knobs, the former being able to keep up with the latter somewhat. Jacobs can also spawn in massive numbers with Big Willies or any boss type, also the most dangerous with Blitzers and Knobs (and with the Mars dlc Cathys).