Well it's maybe not a finished game at the moment but I'm having some fun with Cortex Command, so 9$ isn't very expensive for a quality game.
Have a look to the demo :)
http://www.datarealms.com/devlog/cortex-command/black-friday-sale-get-cortex-command-for-9/ It's not good to say a game's not finished and then try to sell it. We know it happens but normally publishers aren't as obvious about it ;-P
Mount&Blade was available to buy for 3 years, yet the authors just released the full version 3-4 months ago. I bough it last year and I'm glad I did.
www.taleworlds.com
I would never pay for a pair of shoes and getting only the left one (the rest when it will become ready.)
What if the shoe is 1/3 the full price when you get one and wait for the other? And we are talking about a playable game not a shoe. You can't walk around with one shoe and one foot naked buy you can play a game which is constantly updated. It's much like buying a game engine and get some features later via updates.
@Mortiis: lol, no thanks, I insist...