zazzorik

I'd like to point out that both Mike and the guy that wrote the journal mentioned that the place looked comfy or better than their current living space, possibly meaning that it makes you want to stay. Also, the tunnel, since it was unlit was likely sealed by that door for a good reason, as it was just dug out and had nothing in it (Aside from whatever was following Mike and Dave). That'd imply that the construction crew may have found the tunnels and sealed them before being killed (Hence the burnt body) or abandoning the whole place. Edited, just adding that the guy from the journal also states that the tunnels are an attractive housing option and is full of food and seemingly perfect. It's possible that this is how whatever lives there feeds, by luring people in and killing them, before moving on to the next person.