I used to play a game called Alternate Reality a long time ago.
It was a single player game, but what made it so amazing was the realism. For example, you could look in the sky and see the sun slowly rising in the morning and setting in the evening and the amount of light would adjust accordingly. At noon it would be the brightest and gradually it would grow darker as the sun set. If you wandered the streets by day you would run into merchants, nobles, commoners, fighters, gladiators and other citizens, but if you wandered the streets by night there was an increased chance that you would run into muggers, bandits, monsters and other bad guys. All the NPC would react differently to you depending on your alignment, which was based upon your deeds, similar to UO.
Anyway, if you did not go to the tavern and eat or buy food packets to eat on your travels then your skills eventually slowly began to deteriorate as you became hungry and thirsty. First your character would become Hungry or Thirsty and this would have no effect on your skills. If you did not go to the tavern and eat and drink you would eventually become very thirsty and very hungry. At that point your skills would slowly begin to temporarily deteriorate. Go even longer without food and you would go through different degrees of hunger and thirst until your char was Parched and Famished. Your skills would begin dropping rapidly at that point and you be at a great risk of being killed with almost no skill left and would need to make your way back to the tavern to have some roast dragon and wine or whatever you could afford.
The same with sleep, if you did not go to the inn and get some sleep, you began to get weary, then very tired and so on until you were exhasted. At that point your skills would also begin to drop. When you slept at the inn time sped up though, so you did not have sit for eight hours.
If you never ever ate any fruit or drank any fruit juice you would have a chance at getting scurvy.
You could store your gold in varying banks, but there was always a very small risk that the bank might fail, but you did earn interest on your copper, silver and gold depending on the level of risk.
When you bought something from an NPC, you could barter with them, but if you offered an offensive price, they would kick you out of their shop, so it was a little tricky.
It's a really cool game, I almost want to go play it now after writing about it. I wish UO was more realistic like that.
It would be cool to go to the tavern at the end of the day and chat with fellow UO adventurers who were also having their evening meal and drinks, but there is no need to.
Gameplay - "There was no game I could find that matched the variation and complexity of Alternate Reality the City (although Ultima was pretty close). Developing character dynamics through social interaction was cutting edge for its time. There were so many things you could do in this game: buy a drink for the people in the bar, sleep on the cheap floor in the cold corner, drink wine instead of ale, feed the poor, trick a thief and steal his money, wear metal armor, learn spells, open a bank account, find secret passage ways, and so much more. Compared to most games in the 80’s, the realism of survival in an unfamiliar city and the complexity of the game earns a perfect 10 in my book in game play. Moreover, having a meaningful story behind the game plays a significant role in being involved with the game. Keep in mind that The City is a role-playing game. Unfortunately, there are some people that don’t like role-playing games."
http://www.ataritimes.com/8-bit/reviews/altreality.html