1) How much value does the feature add? The more value it adds to the time I spend with the game, the more I might be convinced to acquire it rather than wait to unlock it.

2) Does the “locking” feel artificial? The more the feature feels like it should be readily available for all players, the less I’m inclined to pay for it (or play the game at all)

3) Does the “unlocking” feel artificial? The more the unlocking process feels like a tacked on mechanic that doesn’t add to my enjoyment, the less inclined I’m to pay for it (or play the game at all.)

4) How much does the unlocking cost? The more the price seems like a token monetary commitment for avoiding a part of the game I personally dislike, the more inclinined I’m to pay for it.

5) How much value have I gotten from the game. The more value (enjoyment/entertainment/etc) I’ve gotten from a game, the more I’m inclined to give money to the developers.

6) Is the locking preventing me to play the way I want? The more the locked features allow me to play exactly what I want, the more inclined I’m to pay for them.

7) Does it feel like I’ve purchased an incomplete game? Sunken costs get people on this one: if you feel you’ve already invested a lot, you’re more likely to purchase the locked features; if the prevailing feeling is one of disappointment/betrayal, you’re more likely to stop playing.

I admit, I have objections toward this model too. There are many things, which I dont like about this model, but lets stay with your comparison, which I think is realy good to think about.

If pay-to-save time is like a trial, than why the game bothers me constantly about all the stuff I could have (actually buy)? So instead of tryin the game and knowing, that I have this limited amount of time or this limited features I play with the awareness, that I have all the stuff, this game will ever offer, I just have to pay for it.

I dont know if it becomes clear. I meen, this is a kind of a known merchants trick. Have you ever been on a Turkish bazar? How do they sell things? They put something in your hands or even direct in your bag. So this great object is instantly yours. And what you own has psychologically more value than something you dont own. Now all you have to do is, to pay.

For me, its a way of persuasion I dont like. Furthermore, when I pay for stuff in a free to play game, I buy it bit by bit. But when it is a trial and I testet the game and I actually like it I maybe want to buy it. But I cant! When I buy the game I want to have it all.

I think there are another questions: What do I realy buy?
- features?
- play time?
- gimmicks?

Imagine this:
You are sitting in a movie theatre and watching a free to watch movie. And its OK, yeah, you like it. But in the third scene the movie pauses, someone from the staff comes in and says: “Hey, the next scene ist reasy great and for only $1 you can watch it.” And you say: “I dont know. I want to try it a little bit more, show me the next free scene.” The movie goes on and every second scene your are asked to pay. This … is … not … fun. Not at all. I want to test – pay – play. What you get with free to play games is a never ending loop of test and pay.