i think that its actually a really cool idea and very innovative. I haven't yet seen a game where you are completely vulnerable with no ability to attack until you gain the power up. I think as far as attacks go you could go really far with this idea. Some could make him shoot. some could let him suck the life out of others. You could sometimes give a shield( not really an attack but could be useful). I love the idea.
I'm sorry that someone chose to be negative and ruin the space for some critique but i truly think thats a great idea for a game.
