My suggestion would be most games form
Choice of Games. All the games are text based and give you the choice (ah haha) of picking the rout you want your character at that point to make. The sight itself makes the games, but they also allow hosted games from people who use their files to make them. And since they are hosted, people can sell them legitimately in the App store, Steam, Google Store and even the sight itself. Not bad right?
My favorite games from the sight are Tin Star which is over 1,376,197 words long. You'll read 80,000 words each time you play!
The down side, if you count it, is that you do have to pay for a majority of the games. Some of them are free, but those you do have to pay for are pretty cheep. Even ones that are vary popular don't go above $5.00.
So yeah, that would be my suggestion.