The next stage is where things really start to heat up. Each scrolling tunnel is chock full of different enemies such as flying saucers, bats and chomping jaws, all of them focused on taking you out. Your goal here is to kill them off and go on to the next tunnel. You'll lose a life by colliding with an enemy object or with the skulls embedded in the tunnels' ceilings and floors, while contact with any other area of a tunnel's ceiling or floor will merely cost you points.
Following the tradition set forth by Demon Attack, Subterranea offers a mindblowing repetoire of adversaries, each of which varies in speed or numbers, or the ability to defend itself. The first tunnel of the second level features swarms of bluebirds, of all things, all firing away at you with missiles! The cast of characters in Subterranea is rivaled only by Activision's bizarre Megamania.
Imagic had, by this time, perfected the illusion of momentum, so your ship responds to your commands as if it actually had mass, fighting against inertia when you power your engines, and coasting to a stop when you release your stick. Adding to the illusion is that the tunnels, in addition to scrolling smoothly horizontally, also scroll slightly vertically in response to the up/down movements of the ship, creating a realistic cinematic feel, as if a camera was trying to follow every movement of your ship.
Subterranea is yet another example of Imagic's attention to detail and its focus on quality over quantity, despite the prevailing market-driven attitudes of many of its competitors at the time.