So, the game was previously not actually 'sold'... it was provided free in exchange for a donation above $5. Weird, I know, and it makes very little sense all around, but that's how the transaction worked.
The 'premium' version that will be released, will be a permanent purchase of the game. Think of it like signing up for Early Access on Steam, where the game is a little cheaper in exchange for not being entirely finished. All future versions will remain purchased, and any change in price will not impact anyone who previously purchased the game. It's yours, and unless I drop dead and never finish it, you'll eventually get the full final version for no additional cost.
Since I don't want anyone feeling like they were ripped off, I'm making sure that everyone who ever spent money to support Rewind will get at least the amount they put in as a coupon code towards the full purchase. I know that the bump in price will lose some customers... but, honestly, I've worked on this game for a really long time, and at this point I really just need to come out and say that it's worth more than five bucks.
Right now, the plan is for the full purchase price to be $25. I intend for the initial sale price to be $15, and that sale will last a week, so that people who are already following the game will have a chance to pull the trigger at a lower cost.