Tails of the DARK SEA forums discovered an interesting feature found in the Ecco 2 Prototype. When you first begin the game right after the prologue, hold the UP button during the sequence where the Vortex Queen falls from the sky. When you press START the game will begin in two player mode with two separate life and air bars.
Both the first and second players are restricted to the same screen. If you try to wonder or jump off screen the other player is forced to follow, dragged through the barriers, .
Whats funny about two player mode is the second player can harm the first player and vice-a-versa. For those wondering what an Ecco the Dolphin fighting game is like now is your chance to discover it.
Two player mode is fun but has its quirks; you cannot pause the game as the second player or try to bring up the sonar map. Since the Ecco 2 Prototype is unplayable in a linear fashion you will need the cheat menu to travel to different levels. To access the cheat menu make the first player face the screen and press the C button eight times.
According to Tails the Ecco 2 prototype is the only version of Ecco that has a second player mode. If an earlier version of the Ecco 2 prototype exists it may feature the second player mode as well.
Source: DARK SEA - Ecco II "E2A" Prototype [Build Date ???]: Debug Features
