I currently have the Android version but want to play on my computer, do I need to purchase the game again?
You are correct. A separate purchase is required to play on Android vs. Desktop (Win/OSX/Linux).
One silver lining, however, is that the desktop version is regularly discounted at 75% off these days. It's usually not long until the next sale!
Dan Fedor - Founder, Blue Bottle Games
Much obliged to you for posting that it very well may be only what to offer motivation to somebody who needs it! Keep up the extraordinary work!