Metismo has recently released Vektrax [App Store], a 3D tunnel shooter for the iPhone built on the company's Bedrock cross-platform development environment.
In Vektrax the player controls a ship barreling through a tunnel landscape littered with enemies. The goal is to destroy said enemies and make it from checkpoint to checkpoint before the timer runs out. Booster fuel accumulates as enemies are destroyed and allows for temporary speed boosts that aid in reaching the checkpoints. The game features tilt-control with a touch to trigger the boosters (lasers are on auto-fire).
While I find Torus Trooper to be the more engaging game, this iPhone adaptation of the formula provides simple shooter fun. Hopefully the developer will include a soundtrack in a future version of the game--this initial release features only basic explosion (and the like) sound effects.
Shooter fans--and particularly fans of Torus Trooper--should find the game worth the $0.99 admission fee.