I had a series of games that I made called "Bad Farming", it was like the old school drug wars, but with farm animals. The series included bad farming 1, 2, 3, and the expansion to 3.
1 was a very simple program where you could buy and sell, and get money. There were random prices (IE from 1-5 for pig, 20-30 for cow, etc...). The system required you to put numbers for things you wanted to sell.
2 was more in-depth, having supply and demand random "Blowouts" that increased the price thrice-fold. Here, you had to pay Giovanni by the end of 15, 30, and 60 days, in different amounts starting with 3000 to pay off a loan. This installment included cheat codes, including turning the farm lingo into drug lingo by entering your name as "Giovanni" on the "Enter name" screen. This system let you type things like "Sell Chicken/Buy Chicken/Skip Day", etc... but suffered from problems like capital letters, and small mistakes, where you would waste a day by entering the incorrect syntax.
3 was much like 2, with graphics (very poorly pixel drawn designs, etc...), an ability to "save your game" and play beyond 60 days, and several other game tweaks. The expansion added more animals, and an options and credit menu, where you could set several different options from the color of text, to graphics on/off, etc... This system was very user friendly, where you could misspell several different ways, and still have the game understand you, like "Sell Chicken" or "sell chicken" or "sel chiken", etc...