I've never played the Sims myself, but I have played Creatures. It's an artificial life game for PC. It's a very realistic virtual pet. You raise and breed norns, with kits and scans that get very in-depth regarding their biochemistry, brain activity and drives, etc. There are different kits which allow you monitor and inject chemical agents into their body, monitor their body and general health, track fertility, analyze their genetics, etc.
It's interesting in that they go through a complete life-cycle: egg, infant, child, adolescent, adult, elderly and eventually death somewhere in there. There might be an extra "stage" or two of growth in there as well, as they get bigger as they mature, and their features change as well. I've personally had not so much experience in death, as there is a mutation commonly referred to as the Titan gene, which allows them to live ridiculously prolonged lives, possibiliy indefinitely? They more or less become immortal, at least with regards to aging.
You also have to actually teach them and train them. You can look through their eyes to see what they're focusing on with one window. If you get its attention on something, you can repeat the name of whatever its looking at and it will gradually learn the name. This makes it easier to communicate with them and figure of what your Norns are thinking/feeling. They act of their own will, and eat/sleep of their own accord too (you should train them and reward them for eating, but that doesn't mean they'll always do it... trust me -.-'). They also tend to get distracted around other Norns a lot easier.
The cool part about breeding is that there are different breeds of Norns (including some interesting third-party breeds, complete with custom sprites, genetics, behaviours, etc). When they breed, they create truly unique, individual offspring with their own genetics and unique DNA, just like in real life. Through successive generations, different mutations also develop with can change the way they look or are pigmented, give them prolonged life and strong vitality like the Titan gene, etc.
It's also neat because they inhabit their own world, complete with its own ecology. It's fairly big and has different zones with different "technology"... elevators, toys, types of objects. There are different types of food and herbs that grow, including dangerous, toxic ones. There are also different races, like the Grendals (reptilesque creatures which are allegedly "violent, toxic, evil, bad", etc.) and later, in Creatures 2 and onward, the Ettins (they like to take stuff apart among other traits). There are third party add-ons developed for raising your own Grendals and Ettins, including the sprite and game data for female Grendal/Ettins (Grendals are laid by the Grendal mother, male only. Same for Ettins, forget where/how they spawn tho).
Really is a fun and interesting game, I would love to try it again sometime, if I ever find the time for it between life and other games.