I've been seeing some clips and pictures of your game and now I just tested the game myself. The game looks very promising so far, you did a really good job!
I've already read somewhere that a sub-mode is in works, this is what I'm mostly hyped for!
I was also thinking about what would be possible to add, which also puts more depth into the gameplay/difficulty itself.
What I thought of was some kind of weakness profile in the character creator, where you can assign ticklish spots or weaknesses in general (with intensity from 1-10) to adjust the difficulty in that way and so NPCs will figure out more and more of your weaknesses the more often they capture you, until it's almost impossible to escape if they utilize all your weaknesses.
In terms of weaknesses it can be obviously different ticklish spots like feet or belly. Tickle Tools (Hairbrush, Fingers, Feather), and some other weaknesses, like being gagged or blindfolded or tied up in a specific device.
Another Idea for the minigame for when you will be tickled could be, to keep the mouse inside of a moving zone in the UI, basically to keep your composure. if the mouse leaves the zone, the tickling becomes unbearable and you take "damage". Being gagged and blindfolded could have some negative effects for the player here aswell, like being blindfolded, makes the zone invisible for short periods of time. Being gagged increases "damage" you take and your ticklish spot intensity multiplies the speed at which the zone will move.
Those are just some ideas I wanted to share. I'm really looking forward for the next update and getting tied up and tickled by NPCs! :D
Keep up the good work, this game has huge potential!