Master of Orion I & II (III is apparently terrible and broken).
They are quite old but they should run fine
Pretty much anything from here will run for you:
http://www.gog.com/en/frontpage/
Are they worth it? I mean sure it's just 5 bucks for one of the apparently greatest games of all time, but are you gonna play it? Sometimes I buy old classics like that and I just end up not really playing it.
This week-end on gog.com, they had Creatures 3: Exodus on sale. It's an awesome simulator. Seriously I don't think there is AI or modelling as advanced as this in any game, even if this game is over 10 years old. You're basically on a space ship that is equipped with all kinds of ecosystems that you can grow various breeds of sickingly cute creatures called norns (there are other creatures too, but you mostly dabble with norns). There are machines like gene splicers, gadget replicators and whatnot. They are actually haploid creatures with a programmed genetic system and they pass stuff to each others, like behaviour and appearance and whatnot. There are over 200 chemicals programmed in the game (antigens, glucose levels, fatty acids, bacteria, toxins), you have medical scanners for the creatures to monitor what they're doing. You can teach them language. They teach each others stuff. They have emergent intelligence basically. With the exodus version of the game, you can send your creature in the containment area and ship them to other player online who put them in their own quarantine and decide what to do with them, if they like them they can use them to inject their genes in their own colony. It's awesome, except for the fact that, as I said, it's sickiingly cute and makes me question my masculinity.
Oh yeah, and all the gadgets on board have outputs and inputs and you can link them together with simple programmation. You can plug a creature detector to a gun and it will shoot when it detects the creature that you set the detector too. Or you can put a scent emitting device to attact monsters in the airlock... And put a monster detector there that is linked to the airlock's ON switch. So when the monster comes in. WOOOSH. Sent to the vaccuum. I used a graphing gadget to make a chemical detector, when a creature walks by I know its protein or starch needs and whatnot.
It's
Anyway, there isn't really a specific goal, and you can basically watch it run without interacting much. It's kind of a toy, but it was only 5$. It's just sad that there are basically no people left online to exchange creatures with.