Interactable items within rooms that can cause damage to enemies. Below are a few examples for rooms for a home scenario.
Kitchen: Pots, pans, knives, bottles in the fridge, the fridge door, plates, forks.
Dining room: Dining chairs, plates, forks, knives.
Living room: Lamps, books, pillows, picture frames.
Office: Monitors, keyboard, books, letter opener, picture frames, lamps.
Garage: tools, power tools, spare bits of wood.
Bathroom: soap bottles, toilet lid and water tank lid.
Soft items like pillows and soap bottles wouldn't kill but would stun the enemy enough to either reload or deliver a punch or stab.
I know the physics could get tricky with all of the loose objects sitting around to bump into and I know nothing of game development but would it be possible to make the objects static until a player grabs the item to save resources?