Free-to-play is the new Shareware. Shareware was a neat distribution license back before internet, where the product (fe. a game) had a limited feature set and the user had the right to further distribute the copy1. Here, the author banked on the features of her product and the goodwill of her potential customers to create a customer base for her product. If the potential customer was pleased with the product, she could pay for the complete version of the software.
The key difference, in my opinion, to demos and trials was the explicit agreement that the user should be involved in sharing the product and in return, the author had opened up the product more (or so it was assumed) than in a traditional demo or a trial version.
A notable example of this was Doom.
Like a gene or a meme, only a good shareware game would be passed on to other BBSes or on a floppy (later even on CDs) among a group of friends.
The challenge of the shareware model was how to balance the content in the shareware version. A widely used model in games like Doom and Duke Nukem was that the first episode was free.
Another challenge were international payments and postal logistics, both of which probably didn’t help conversion rates.
These days internet has removed the barrier for distribution (for the shareware versions and for the pirated version), so shareware is now mostly a meaningless term. Before the internet, only the best demo versions were called shareware and the rest were labeled with derogatory terms like crippleware or trialware.
There are clear parallel lines with “free to play”. The game itself is free to acquire, but is limited either explicitly or implicitly - the idea being that you are strongly encouraged to pay if you want to have the full experience. The model hinges on the network effect, the happy users will recommend the game to his social circles. The unhappy will label the product with “pay to win”.
The internet having solved the logistical problems involved, the challenge has become to optimize acquisition, conversion and virality potentials. In the world of BBSes and floppies, these processes were almost invisible for the author, but they are now the key metrics to follow.
The danger with free to play model seems to be that the conversions and virality are taken as an assumption. The player is expected to pay and recommend the game whether he likes the game or not. The two-sided agreement with shareware is now an one-sided agreement, where the author gives an explicitly crippled version and expects the player to want to think it’s the best thing ever. There was never anything “free”, but the player is expected from the first launch to rate the game 5 stars and share it on Facebook and earn her right to play the game.
However, this is all acceptable because on aggregate things seem to work. However, in the long run this will destroy the social contract between authors and the players. The creators pretend to give the players enjoyable experiences and they, in turn, pretend to like and recommend the creators’ product.
Just because your F2P game is technically the “full” game that can be unlocked by paying doesn’t mean it’s free to play. Remember, this was true for many demos and trial versions as well.