Project Black Sun came out of nowhere and surprised me. Two-man team Starflower Games has produced a refreshingly back-to-basics platform roamer - a distinct homage to Super Metroid - and it's a joy to play. Black Sun scores major points for its gorgeous art and music, tight gameplay, and classic atmosphere.
Beyond the brief introduction, there are no cutscenes or friendly characters here - just a sprawling, silent, multidirectional maze full of secrets and powerups, Metroid-style. Controls are tight and responsive, but they take a bit of getting used to - you can only fire horizontally, and you can't fire while jumping. This felt like a handicap to me at first, but the game is actually balanced around these restrictions, so once I got used to it, I didn't even notice anymore. Reloading is a bit trickier - you are extremely vulnerable while reloading, so you have to think ahead during boss fights.
Black Sun's difficulty level has been a problem for some. The version I played, 1.0.2, apparently smooths over a few issues. I found the game to be challenging, but very approachable and very winnable. The early game can be rough, as you have few bullets and very little health, but once you've found a few powerups and gotten the hang of combat, making progress gets a lot easier. There are a handful of unfairly-positioned enemies here and there, but they don't detract much from the big picture.
The only glaring difficulty problem I see is with the first boss, Chrosios, as his cave-in attack can be very difficult to avoid. If you're having trouble, I recommend skipping him and moving on to the second boss, Anyos. Anyos is much easier, and his key will let you pick up at least one more heart container, which will make a big difference against Chrosis.
All in all, there's a lot to like about Project Black Sun for fans of Metroidvanias, and there's a fair bit of content here for such a low price (my first playthrough took me a bit over seven hours to complete). Starflower Games has definitely gotten my attention.