Incentive for killers to not hard tunnel
Basekit incentive idea:
Everytime you hook a survivor for the first time you win a stack (max 4), when you get all 4 stacks AND all survivors are alive this basekit activates permanently.
Each survivor consumes one token (max 4). Each token regresses the generator with the most progress by 15%.
The killer can still hook the same survivor twice in early game if he wants to, or hook twice after the basekit is active (tunnel after 4th hook and get 15% in his 5th, first kill in 6th and no gen regress but before it he has to find everyone, chase everyone and hook everyone).
Remember the 4th survivor can hide, the killer can get more than 4 hooks before this basekit activates, this basekit doesn't work during endgame and perks like pop, pain res, grim embrace and no way out works with and without hard tunnel.
(Sorry my english is a work in progress 😅)