Wow, that was extremely impressive! The first unexpected happening caught me completely by surprise, and you did an absolutely fantastic job at creating the atmosphere. I adored the environmental lighting (especially when I think some lights seemed to flick on while I was exploring), the ambient audio, and the unsettling ambient musical notes that I think started playing while I was working on a task.
Despite the model geometry being simple (which is of course a good idea), I loved the amount of detail you managed to put into the environment--especially the little touches at the beginning like the tables and chairs, the cash registers, and even the shiny monitor screens. Extremely impressive attention to detail.
I won't spoil any twists here, but I like how the player's speed changed--another nice little touch.
First game jam entry?! Wow. But surely not first game?
Also, I really like the juxtaposition of horror + pizza delivery. Very nice! :)