The Spy's going to have disguising and feigning, riiiight?
A 2D enviroment (and more importantly, in a game like GG) pretty much nullifies disguising and feigning, since players have a wide range of view, thus seeing you before you can even put your disguise or when you "suddenly die" without taking any damage. Perhaps the only way those things can work is if they're an added effect to a certain attack (like stabbing).
Stab an enemy, no corpse is left (or perhaps the enemy's corpse is replaced with yours

), you get automatically disguised as your victim. Your name is then colored to match the enemy team's. You lose your disguise if you pick up the intel, get hurt or if you press m2 (you go invis, but lose the disguise or something. I don't know

). I believe this would just become pretty confusing and would make the general gameplay less fun and more confusing. The same thing could be said about feigning
Until someone comes up with a better way to implement disguises or feigning into the Infiltrator without making everyone's head a mess, you might as well just stick to your infinite invis ability.