"Imagine killing people underwater in the lobby of the Empire State and Chrysler buildings with bees that burst from your arms."
"Real time mutation that affects enemy behaviors while shooting folks with a Tommy Gun"
"The little guy in your fish tank trying to maim you with construction equipment while the scary girls from the Shining drain corpses of mutagen you'd kill to have."
"Ayan Rand, Jules Verne and Metropolis under the sea with you trying to escape with your humanity and your life"
"Imagine high society mutated and after your life. You're trapped and have to kill your way out of the Rockefeller Center on the sea floor. Now the rich shall EAT YOU!!"
"The swinging 60's and you've escaped an ocean plane wreck to a bunker under the sea that's slowly being reclaimed by it."
"Enemies with as many flavors as you and the AI to turn on each other if it means they get to finish you off"
"Forbidden Science and it's abominations hunt you in the underwater hell of an
Art Deco warzone"
"Titanic with guns and hideous super powered mutants. Pretty design and logical levels."
Tried to make each 10 seconds worth of game enthused banter.
Hope some of them work for you.