How to make a slow stealth game feel satisfying?
As the title says, I'm trying to work on a prototype for a stealth game very heavily inspired by the tenchu series (in specific tenchu z as I've played it for hundreds of hours) and still being a noob, I need suggestions on how to make the gameplay feel good but not fast, one thing that I know I'll spend a lot of hours trying to get right is the kill animations as those are definitely part of the cool factor, but aside from that what else? I've played plenty of stealth games and the level design, core stealth mechanics and takedown animation are always the main attractions, what else could be implemented to give the game more punch? Collectibles? Side objectives? Mini games?
Edit: thank you all for the suggestions! it definitely helped me see what i should focus more on at the moment which is the gameplay feel, tense risk and reward stealth and general good audio for the games atmosphere as well as other suggestions that gave me more ideas and details to add.