What you need to do is talk to the hunter, get the rifle, equip it in the inventory and start leveling up. In the house where the grandma is there is a ladder, you can bring this ladder to access new areas. Once you are strong enough (about level 5) you can kill the Sickened Spirit, north of the weird tree. At the end of the hospital is a rope, you can use this rope at the well to access the final parts of the demo. If you wanna go easymode you follow these tips:
1: Equip Jack of Traitors for most combats, but Jack of the torpid for the combat against Euthanasia. Choose powerful after killing the deer at the killing fields, this is a "mood" which raises your attack significantly. The fishguys at the lake are a good source of XP for leveling. Choose "bad" as your intent once you have gotten the rifle, this also raises attack. Then its time to smoke some enemies.