@Zergling_man what i mean is that l4d2 by default has no xp or level systems, no perks and traits either that were in swat
so like baseline, you could easily recreate swat's gameplay for the most part, minus the curing the infected part, the generators could be fueled with gas cans instead of mana, the rad shards could be easily made into func_breakables that you need to break to complete one of the goals