I covered the basics of gameplay in my E3 preview. This time, I'll focus a bit more about some things that I didn't cover as much: the visual styles, the bosses, and the bonus modes -- at least for the three worlds I've experienced.
Gallery: Big Bang Mini
The first world, Hong Kong, renders the avatar as a rotating purple triangle flying over a brightly-lit 3D night cityscape. In this world, you shoot fireworks at balloons and traditionally Chinese things like pandas, dragon floats, and ancient rocket-style fireworks. At the end of each level is a bonus zone with a series of numbered dots, through which you drag your "ship" in the correct order to reveal a picture.
The boss at the end of this world is (what I believe to be) a lion statue that fires shmup-style bullet patterns at you. First you must destroy two bubbles that surround him; then you have to blow up multiple forms, each with a different, rainbow-colored bullet pattern.
The next world is Aurora, which switches the city for a snow-covered field (with snow on the screen falling to indicate the new wind element), your sprite for a snowball with a thick black outline, and the enemies for ice blocks, flying fish and hockey-playing birds. Instead of fireworks, enemies explode in a snowflake effect. Not only the images, but the style have changed to a more cartoony, less shaded look. The only common graphical element is the star that falls from each defeated enemy. Even the bullets have outlines. The bonus zones involve the same connecting of dots, but the dots now have ice that must be tapped away before tracing.
The boss is .. a punk-rock walrus on a flying carpet who attacks you with auto-targeting, flashing fish skeletons.
I can't tell you about the boss of the third world, Kamakura, because ... I haven't reached it yet. By now, the enemies are really fighting back, sending all kinds of junk into the bottom screen. This world is influenced by Japanese ghost stories -- it's a dark forest colored in lots of green and purple, with glowing ghosts as enemies. In this world, as time passes between destroyed enemies, walls begin to close in on you on the bottom screen. They retract a bit when you blow up another enemy. You gain homing missiles in this world as well, launched by holding the L trigger when you attack. In the bonus zones, the dots are covered by encroaching foliage. Tapping temporarily clears an area away.
Having such a simple game and simple elements, including a nondescript player character (really, it's just a ball or something in most stages) and a simple mechanic has enabled Arkedo to use completely disparate visual styles from level to level without making the game too confusing. Even if it looks like a totally different game, you're still scratching upward to fire at floating enemies!