just walk off the top of the garage towards the purple light i also got stuck there for a few minutes
It worked once, i got in a tunnel, but restarted because i missed something. Next try i just jumped off the roof and ran towards the light. I met 2 aliens in the woods and it went dark. then I was back at the shed and filled the tank and went to the church. But now i missed that tunnel. At the church I beelined towards it, got sidetracked, went in and went on. I ended at a purple light with ppl floating and that was it. Pretty short, i probably did a speedrun and ignored stuff but not intentionally.