Survival Mod can make any standard or custom maps in COOP more challenging by spawning more suspects at the round start or in multiple waves during gameplay.

Survival Mod may be currently hosted in various public SWAT 4 servers, but now you can also download the mod and play it on local server or with friends.

Get the mod here: https://github.com/induktio/swat4-survival-mod

Get also the recommended map pack:
https://www.moddb.com/games/swat-4/addons/mega-map-pack

SEF mod installing help:
https://www.moddb.com/mods/swat-elite-force/tutorials/how-to-install-swat-elite-force

Optional server list patch (only need the TSS file):
https://github.com/sergeii/swat-patches/tree/master/swat4stats-masterserver/