Gunman Clive launched previously on the 3DS, Android, and iOS marketplaces to high praise and great sales -- now, it's on Steam. I'm a huge fan of it personally, as I think it's a great homage to classic platformers of old -- particularly the Mega Man series.
One of the best aspects of Clive is how easy it is to plow through one playthrough -- which takes roughly an hour. Not only does this faithfully replicate the NES era in terms of length, but it also ensures that no portion of the game overstays its welcome -- and with a $1.99 pricetag, it makes perfect sense.
I had a chance to play the recently released Steam version, and it's basically the same game people have been enjoying for about a year now. It's a very basic port with no additional content, but it comes with controller support, a higher resolution, and extra achievements. The game natively supports 360 controllers, so if you have something else, just get your PC to emulate one by way of x360ce.