Addictive
This particular game is jam packed with the sort of cut and thrust archery that keeps you coming back for more - getting the achievements in game is tough enough and the Newgrounds medals on top of that are difficult but fun to try and get.
I'm not entirely sure how much of a benefit the armours are, but it's a well thought through system linking them to the achievements. Perhaps another way to do it is to have them available for the survival mode when you've unlocked so many achievements, for a start, but when you're in the shop, you should be able to buy them in the campaigns. Perhaps this would require more gold being dropped in the game to cope with the extra budget required.
[Review Request Club]