This one's probably another repeat, from long back. I was also hesitant to post it since it's basically an online version of an older console game apparently, and I dunno what's going on there with copyright and stuff but... it's been up for years and I don't see the game owners having issues with it and taking it down or anything so:
Game type: Text-based, web-based life simulator
Time demand: Decent, maybe an hour or two to get through a "life"? I think you can save and come back though. I'm not certain.
What it is:
As I mentioned above, I think it's an online version of a console game, but I never played (or even saw) the original, so I can't give details. You start out answering some questions about yourself (or skewing the answers to make the online "life" a bit different), then you are "born." After that point you select various types of events to see, and make decisions on what to do. How you grow up and how you live your life afterward depends partly on the various choices you make.
It's fairly straightforward: you click on part of a tree of various events, see an event, move through it, possibly get some changes to your personality or whatever, as you grow and develop. As you get to older childhood and eventually adulthood you can also do a few other things, like buy a house, concentrate for a bit on school or work, or on romance. You can get married and have kids.
Eventually the inevitable happens, and you get old and die. Sorry about the spoiler. How old you are at that point depends I guess partly on luck, partly on how you've lived your life up until then/how healthy you are. There's no over-reaching goal, it's just a kinda neat time-waster, to live another version of your life for a while and see how it turns out.