Meh, fairly good. Easy enough that I finished it in just over 4 days on my first go. Just sit on the lab and dodge out of the way of anything that gets too close until you can get top level research skill, then go for reload. Heal from the shop when you get low and get accuracy to max. Buy weapons as they become available, but once you have the rifle and high reload speed, it's cake. Stay on the lab until you have every skill at the highest level (tree growth last). Grow the tree, and then stay to the left or right of the screen with the tree on the edge of your vision. Shoot at whatever comes with the microwave gun. Win.
The reason that it says that you've already added the pieces is that it will tell you that you have already collected it ON MOUSE OVER. It will check this every frame, so unless you move the mouse off in the 1/30 of a second that it takes to change frame, you'll get the message. Also, stolen. While I'm not usually quick to accuse a thief of a game, unless the uploader is from KranX, or has managed to get it on Steam without KranX knowing - which they do - he is indeed a game thief.
Could you not have kept the AG global saves in this one too - even just the badge-relevant data? While it's a great game, it's not good enough to play through again just to get the badges that I have already done, but not on this site.
At its most basic, rocket science really isn't...well, rocket science, I suppose. It's basic conservation of momentum. When you have to factor in gravitational fields, and moving targets and starting points and stuff, that's when it gets more difficult.
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