What does your Character do?

My partner and I have been working on Spectra, a two player cooperative puzzle platformer, for our Intermediate Game Development class at USC.

 We set out not to create just interesting game mechanics, or to tell a touching story, but to also address co-operative play between two players.

Mirror Images
Today, whenever the topic of co-operative play comes up, everyone is quick to refer to Portal 2, which includes a two player campaign alongside its main single-player story. Valve was very successful in crafting an entire experience around their two player mode, stringing together a set of new characters, voice acting and a narrative.

However, these new puzzles are essentially Portal levels that involve a second set of portals. The two players are mirror images of one another, have the same controls, the same portal gun. players have swappable roles, 

Two Layered Cake
Spectra's co-op gameplay is different in that the two players abilities are directional and can be layered on top of each other. Each player is given the same set of colors: white, red, blue, yellow. However, they differ in the way that they use these colors. Games like portal 2 had a straightforward evolution to a two playermmode. It is, however tough to go in the other direction, creating a single player experience out of a multiplayer one. Part of our purpose for creating spectra is to bring two players closer together and feel the intimacy of the hero and heroine. The removal of either of the characters breaks down the structure of control. to use an analogy, Spectra would be the equivalent of two players each controlling a single portal. you need both of the portals for the mechanic to be demonstratable. you need two sets of primary colors to create secondary colors.