Heck no! Though I've never been to a convention, i've seen tons of pics and I can't tell you how many times i've seen people cosplaying as characters for video games that hadn't been released yet (like SSBB version Pit before the game had come) or even as characters from animes that haven't even been released legally into the US. So, my point is, if its ok for others to do that, why couldn't you?

Have fun!

"Amor, amor, nada hay peor ni mejor" -proverbio

What do you mean by "unreleased"? As in it hasn't been brought over from Japan yet, or they're still making the game?

Some cosplayers like to go for more obscure or rare characters, so this would fall into this.

That said, A-Kon needs all the video game cosplay we can get for our Guinness attempt - Largest Gathering of people dressed as Games Characters. The only catch is that the character has to be from a game first.

You can read more about the Guinness attempt here -
http://www.a-kon.com/bm/Attractions/a-kon-goes-for-the-guinness-book-record.shtml

Yup yup. I knew that. and i wanted to go as a guy named Alex Mercer from the game prototype, but it's not out yet, and I'd just be going as his human form and not the form with the giant monsterous hands.
that's why I wanted to see if it was a lil dickish of me. Since everyone else is trying really hard to put their costumes together, and all mine is is a white hoody,black vest jeans and tennis shoes.
But he will be from a video game though. So I'm not sure.

I go where the wind takes me.