For a little bit of shameless self promotion, I'll mention the Abstract Dungeon Beta Test. It is designed to be very quick and easy. The mechanics a bit different from the typical RPG, so if you want to give them something that represents the hobby, you could try something else.
I'm actually going to go a little bit off of the original subject.
For first time players I think you shouldn't worry about the rules being free. It's a good thing that you don't want them to feel the need to buy the book. I'll go even further and suggest that first time player's shouldn't even need to read the book.
For characters you should either use pregens or simple random creation.
Tell them the basic rules, and if needed give them a quick reference sheet.
The "World" games work well for this. Dungeon World might be a good choice for a first time group. All the info that the PCs need is printed out on a couple pieces of paper so they never need to look at a book.
I'm actually going to go a little bit off of the original subject.
For first time players I think you shouldn't worry about the rules being free. It's a good thing that you don't want them to feel the need to buy the book. I'll go even further and suggest that first time player's shouldn't even need to read the book.
For characters you should either use pregens or simple random creation.
Tell them the basic rules, and if needed give them a quick reference sheet.
The "World" games work well for this. Dungeon World might be a good choice for a first time group. All the info that the PCs need is printed out on a couple pieces of paper so they never need to look at a book.