As you progress, you'll get new kinds of bullets, with some that split into three separate projectiles and others that explode in a four-way shot when they run out of power. There isn't much explanation in the game for what each shot type is or why you get it, but after a few games I was able to recognize the different types of bullets by the way they looked. It would have been more fun had I known what I was shooting beforehand or any sort of introduction to new ammo. Angry Birds players will remember that each bird was introduced so you knew how to use it. Stay Alight has no such introductions.
Stay Alight has three themed worlds for a total of 60 levels and a placeholder for new worlds to come in future updates. But another element of the game that is a mystery is a puzzle you slowly build as you play. In some levels you'll see a puzzle piece that -- once your projectile passes through it -- it is added to a larger puzzle you build over time. Unfortunately, there is no introduction to the puzzle either, and I wasn't able to complete it in my testing for this review, so I'm still unsure what might happen when it is complete. I think if I knew beforehand what the goal was, I would be more inclined to see it through.
Despite all the mysteries, Stay Alight is a pretty good game. The graphics are well done, the sounds fit in with the sort of sewer-like monster microbe theme, and the physics are spot on. If the developers had added some introductions to bullet types, the puzzle element, and fleshed out the 3-star rating system, this review would have a higher rating. Still, the game will be enjoyable to fans of Angry Birds looking for something new, but just be aware that you'll be on your own in figuring out what exactly is going on as you play.