At first, I only found bullets and juice in the supply packs on the ground, and I thought the tree required some other sacrifice, so I didn't pick up the supply packs. After walking for a long time without seeing anything else, I realized I should still collect supplies.
When I was quite far from the monster but still visible, it felt like the bullets it fired could still hit me; it felt like there was no way to exit combat. Although the monster didn't chase me when I couldn't see it anymore, theoretically, it should have an exit-combat mechanism.
The game felt very short; after collecting the four sacrifices, there was nothing left to do. I don't know what the gameplay is about. The monsters weren't challenging at all, and neither were the items.
But considering this is GameJam, it doesn't matter. It's amazing that they even made a game; I couldn't even make one myself.