Alien Movie Question

Someone told me about this weird film where aliens turn their legs backwards when walking and are really freakish and the main character turns into this kind of alien as well. I think he already was, actually. Does anyone knows what bloody film is it?
Thanks!

Kind of sounds like The Arrival (1996) but he didn't actually turn into an alien himself. He sort of puts on a disguise and resembles one somewhat.

The description is really vague. How old is this movie? If the main turns into a freaky(?) alien and it's a new movie it could be District 9.

Yeah, pretty sure it's The Arrival.

I dont know the name but the maim actor is charlie sheen!

No entiendo que se pretende con la pregunta

It could be The Fly (1986).

Son dos peliculas the arrival la primera con charli sean pretenden calentar el palneta para tomar la tierra