i found RUSE pretty challenging, not sure if thats your thing or not
This is an old school game and I don't know how easy it would be to find but Lords of the Realm 2 on its hardest setting will give you a challenge.
The hardest challenge I have done in any game was on Football Manager 2012.
-English Hero Achievement-
Get a Blue Square Bet Conference team to the Premier League.
Took me about 6 months and over 500 hours of play-time. 16 Seasons.
If you're unfamiliar with the game/series, then I highly recommend Heroes of Might and Magic 3 on the highest difficulty.
Even for seasoned players, things can go to hell, very very fast in that game.
Although it is an RTS, I would say Empire Earth is the hardest strategy game I have played. It's almost impossible to beat the AI if you play less than perfect for 1hr+ match.
The game was brutal.
Stop this nonsense, if you REALLY want a challenge check out the Commandos series. God damn i have struggled so much in that series!
Tried it first time when i was 12 years old. Commandos: Behind enemy lines that was. Absolutly fantastic game, both designwise and it's just so freaking hard, but when you figure it out it's so satisfying! Graphics never gets old, and if you're up for a very hard challenge i would really, really recommend the series.
Start with Behind enemy lines. You'll shit bricks.
And what's nice (or maybe not) is the progressive increased difficulty the game offer. The first mission is pretty easy, and then onto mission two the difficulty has increased much, i mean like REALLY much. I struggled at mission 2 for weeks when i was a kid :P
X-COM: UFO Defense (or UFO: Enemy Unknown, which is its real name) - it's pretty much the best game ever made. It's old but runs fine in DOSBox and should be cheap on Steam. It's brutally difficult but rarely unfair - the more risks you take the greater the chances that aliens will snipe you from the fog of war, since they can see in the dark and you can't. Then again, some missions will have half of your team dead as soon as they leave the Skyranger...
It really is awesome, though. It has base management, research, UFO interception, UFO recovery missions, manufacturing, economy, squad management, equipment management, alien terror sites... and sequels!
What about Warcraft 3? not as hard as SC/SC2 but it's great game.
When you said simulation, I almost offered you Microsoft Flight Simulator X.
The night is dark and full of terrors...
Cities in Motion focusing on a bus company.
Sins of a Solar Empire, mentioned it before. It's a RTS with fairly deep (lots of research trees) and long games(they can easily last at least 5 hours, I've never had the stamina to finish a game yet ) and does space combat very well imo.
They are both made by the same company, Stardock. One of the bigger Indie devs out there, they take good care of their games.
To declare that a personal, inner experience gives certainty about the workings of the universe is to assign far too much value to one’s subjective sense of conviction.
I’m not that arrogant.
The brain, marvelous instrument though it is, isn’t infallible. It can misfire, seize or hallucinate, and it can do so in a way that’s utterly indistinguishable from reality to the person experiencing it.