I love Bioshock's gameplay because even though its shooting mechanics aren't smooth like Doom's and Titanfall's, there's something special about Rapture and the degree of freedom you have to interact with everything there. You can shoot stuff, use telekinesis to pick up and launch anything in the environment, use an enrage plasmid to turn creatures against each other and spectate their battle, launch frickin' bees out of your arms, hack turrets to protect you, hack big daddies to protect you, knock enemies back with a shockwave, and much more. Everything feels so dynamic and alive - there's a legit ecosystem going on between the splicers, big daddies, little sisters, and robots. All taking place in a setting/world that's truly unique and begs to be explored and revisited. There's still no setting in games at all like Rapture, and I think that sense of feeling immersed in a fascinating place that contextualizes gameplay which gives you tons of options to experiment and mess around there is pretty rare in games.