Okay, that ending took me a while to figure out. I wont ruin it for you, but all the tricks I tried wouldn't let me get past the final "boss". Took a good 15 minutes before I hit a winning strategy.
I really enjoyed this game. The mix of smart AIs and interesting tactics made it much more enjoyable than chasing Quake3 AIs around the grid. The fact that they would work together, try to work around you, and eventually come in behind made it much more challenging than your average FPS.
The horror ambiance came in waves, which was good and bad. By the end I was mostly anesthetized to it, treating it like any other game element. Not to say it wasn't well done and didn't freak me out more than once, just that by the end it has become (ab?)normal.
I look forward to seeing the sequel. If you have a PC that can handle it, and you enjoy the FPS genre - I'd pick it up. Been a very long time that one this hyped paid off.
Now for the bad news... I need a new game! Waaaaaaaaaaaaaaaaaaaaaa!