Life Force

Life Force is the NES branch of Konami's Salamander line - the same power-up-bar shooter DNA as Gradius, but staged inside the body of a living creature rather than in space. The Vic Viper and the Lord British fly through organic tissue, nerve clusters and a giant brain.

Its distinguishing feature is the two-player simultaneous co-op, which keeps the Gradius weapon system intact while putting two ships on screen at once. The game alternates between horizontal and vertical scrolling stages, and losing a ship only costs you the current weapon build rather than sending you to a checkpoint - a deliberate softening of Gradius's harshest rule that makes it the friendlier game to learn. Its organic stage themes and the convulsing brain boss are among the most memorable images Konami produced in the 8-bit era.

• ▸Two-player simultaneous co-op - rare for a Gradius-style shooter
• ▸Alternating horizontal and vertical stages inside a living organism
• ▸Power-up bar with Speed Up, Missile, Ripple, Laser and Options
• ▸Respawn in place rather than at a checkpoint when a ship is lost