Lab Zero games has recently put out a statement that Indivisible will be featuring playable cameo characters from other select games.
When Indivisible is released, you will be able to find and play as characters like Annie of the Stars (Skullgirls), Calibretto (Battle Chasers), The Drifter (Hyper Light Drifter), Juan (Guacamelee), Lea (Curses 'n' Chaos), Shovel Knight (Shovel Knight), and Zackasaurus (Super Time Force Ultra).
On the other hand, these characters will only be playable in Indivisible if its funding is successful, meaning that if you want Annie: Girl of the Stars to be playable in her first Lab Zero game, you'll need to fill the Indiegogo's Iddhi meter in order to make the magic happen.
If you are hesitating to back Indivisible because you have been unable to try out the prototype on your computer, have no fear. As of today, Tuesday November 3rd, you can play the prototype on the PS4.