You have to kill someone. Better prepare!
Use the drawers under the computer screen to find a ROCK (5/5). Use the fridge to find your SLINGSHOT (6/11). On the shelves on the left you can find a BOOK about 101 way to kill someone (6/17). Read the book and find how to kill someone with a slingshot and a flaming rock.
Use the door on the left to go to the kitchen. Use the rock with the microwave below to make it a FLAMING ROCK (8/25). In your inventory use the radioactive rock with the slingshot (13/38). Use the door on the left to leave the house.
Use your car to drive to the coffeeshop. Talk to the guy in front of the shop and conclude it’s Waldo. Use the slingshot on him to eliminate him (24/62).
Game source: A copy of the game was found here on the internet.