Just managed to beat the game again. I unfortunately went insane, but man was it a dramatic finish. With four hours left to go I knew which god was invading, but I was missing one part of the banishment ritual, so I went to a red city straight between where I was and Stonehenge, but the cops started chasing me. Fortunately, I was able to speed off. The red city mission was hunting down a cursed tome, and I had to explore pretty much the entire map before I found it, which unlocked the final rune of the ritual. I ran the hell out of there, the Tall Man on my heels, and booked it to Stonehenge, hoping I would make it in time. That's where I found at that, once you have less than an hour left, it starts counting by the minute. So I arrive at Stonehenge with six minutes on the clock and start tearing through it, running straight through enemies and popping open every container until I got the key-ring, at which point I ran through the entire underground, the counter ticking down all the time, watching my health and sanity degrade. Eventually I doubled back to the start of the map, opened a locked door I'd run past before, and started exploring the new area with two minutes left on the clock. My sanity at this point was zero, the screen was practically all static, and I kept running into boss monsters that cut down my health even more. But I was in action hero mode: It didn't matter what happened to me, as long as I stopped that god. I finally find the ladder with less than a minute left, charge at the rift, rip out the spellbook, and seal away the god of fear thirty seconds before his terrible reign began.
Well done investigator, well done.