I do NOT recommend this game to discerning gamers. I HIGHLY recommend this game to someone who is looking for a cool thing to have on one's LED Projector wallscreen while playing phat beats or haunting melodies from one's "altered states of consciousness special music" folder.
I use Winamp's milkdrop for the beginning of the party, and then when guests are looking to relax and play simple mindless no-consequence gaming in the smoking room we switch to the Polynomial and the music never skips a beat.
Also, I understand the game does get more challenging when you crank up the difficulty, and that's the only way to get the higher level achievements, but I don't use this game for gaming.
The game mechanics are great. You fire your inobtrusive, silent weapon and attempt to hit an enemy this is often impossibly far away, carefully compensating for the great distance by projecting the target's trajectory in your imagination. That's hard to do, so this game is a challenge.
Its best features are the silent weapons fire and the silent seamless transition from getting silently shot to death by nazi robots to silently respawning; your music won't skip a beat, so people in the next room won't go, "Hey, what happened to the music!?"
Also, this game may cause people on drugs to stop talking and stare for a long time. Get an LED projector is my point.
On a side note, have any of you other reviewers actually done acid? This game will not cause you to become every person who has ever lived, so it does not feel like an acid trip. That being said, you should smoke the stuff that was recently legalized in your state before playing