For those of you who haven't figured out the card: while climbing the tower, when you have a view of earth, wait for a bit. The hedgehog will float past. Wait for re-entry and you'll get the card.
Decent game but I'll echo the comments of slow gameplay. The issue I have is with the relatively small field of vision. If you're up off the ground at all, there's no way to see if you can safely drop to the ground or if a drop means your death, giving you the horrible choice of trying to drop safely or trying to jump as far as you can and hoping you find something.
Decent TD game. Nothing really to set it apart from the many other games in this category. Simple (can be a pro or con), above-average art for the genre, no obvious bugs in the (brief) time I played it. Unfortunately tower defense has been done so many times, there just isn't enough here to differentiate it from the contenders.
Turnpike's comments