Jets'n'Guns Gold is on Give away of the day! It's a great 2D Space Shooter, best I've ever played. Awesome upgrades, and the sheer amount of polish is astounding. The graphics are really great, and there are nice little touches in the game - such as a Remote Control thingy that lets you hack auto-turrets, a little computer thing that lets you hax cargo containers you get, etc (which is really fun actually). Also has some gore for when you shoot down the little astronauts that abandon that one cargo ship you just shot down. I've only played for an hour, and I'm just about to start level 3 (of 43).
In my opinion, it's kinda difficult, but if you like 2D Scrollers, play it (I mean come on, it's being offered for free when it's originally $40 with the upgrade to Gold). No spyware or any of those nasty things as far as I've seen.
GGAOTD Link. Site link.Edit: Played for a while longer, at like level 6. Awesome upgrades, I found the Tomato Gun secret weapon, when my ship dies I now shoot out in jetpack form, and soon will be able to bounty hunt. Such fun.