I generally head to two places:
Steam Game Sales and
Rhekua's tracker.
The first is far more expansive, incorporating several different sites (Green Man Gaming, GamersGate, Impulse) but if a game isn't on sale anywhere they won't show it at all. That's where Rhekua's tracker comes in.
I just assume the base price is 5$ now.
Here you go.
http://www.steamprices.com/uk/app/28050/deus-ex-human-revolution
Plus GMG and GamesGate have had numerous sales for it as well.
I've finished a couple of chapters. While the game is absolutely gorgeous, I quickly became frustrated with it's nonsensical puzzles. I ended up taking an exhaustive approach in order to solve some of the puzzles, which in my humble opinion kills any enjoyment in an adventure game.
I think that you should give this one a pass and check out Daedalic's more recent games instead.
Thanks to everyone for the info!
Ok, I guess I'll pass on that game then since nonsensical puzzles tend to drive me mad...
As for Deus Ex, I just checked the stats and seems it has been on sale 14 times. Holy sweet mother mercy.
Let's see... Magicka has been on sale 32 times. wow.
Steam has a huge catalog and many games have barely ever being on sale/featured. One example that comes to my mind is Bloodrayne+Bloodrayne 2. Heh, guess one can track down those "rare cards", aka, games that usually never/barely ever go for sale to compile a list. (Not gonna do it myself, just saying
)
Interesting, very interesting! Thanks again for the info!