Alien is the second stage in Gradius II (NES). This is a pseudo-organic themed level inside of a massive fortress made of metallic skulls and barriers that completely block the flight path. This level is based from Synthetic Life, but with a few changes like the music, color pattern and enemies. The mini-boss is Big Eye, guardian and probably the heart of the fortress. The boss, on the other hand, is Giga, a Life Force boss encountered after the destruction of the level.