LDW (Last Day of Work)’s games are great! They’re all simulations and one of them is even a free full game on their official site! It’s called Fish Tycoon and you can download it here. 🙂
It’s a game about breeding fish and taking care of them. You basically have to find all the seven magic fishes to win the game, and afterwards, for fun, you can try to find all 441 fish! 😀
There’s a free Flash version available at many sites which is basically a demo for the full game (which used to cost money, of course). There’s also a new (released this year) sequel to Fish Tycoon, but it’s only for mobiles at the moment, so… 😉 (But you may want to give it a try if you’re reading this on a phone or tablet, which you most likely are 😉 ).
There’s more at the link above. Go download Fish Tycoon now (and check out their other games while you’re at it! Plant Tycoon’s also recommended)! 😀