Tower defense game Immortal Defense is now is now available as one of those pick your own price deals, though there is a minimum price of $1.75 to cover fees so they don't end up taking a loss on this. Interestingly, this is an experiment in making such a price structure permanent, as word is: "Note that this is not a sale and not time-limited, it is a test of using this model as a permanent price. We can always switch back some time in the future if it doesn't work as well, but we do like this model and hope that it can work as the standard price for indie games, as it has with Jason Rohrer's Sleep is Death."