Prepare food for your old god! They will ask you for a specific meat using their cryptic language and you will need to grab those ingredients from the corresponding crates. After you have the desired flesh throw it into the summoning circle. Be aware that putting more than one chunk of meat could result in unimaginable horrors, but it's faster than one at a time! After you have dispatched of the summoned beast, you will need to cook it on your cult provided prep station at the top of the room. Once the meat has been burnt sufficiently you will be able to feed it to the old god.

Use WASD to move around, Left Mouse Button is the action key, and pressing Space Bar will make your character dash.