It really depends wether the film you wanna make is ammature or profesional. But its a free world so you can write a script about anything really...

Make Love Not War!

The characters and content of a video game, even an old one, are protected by copyright so in most cases you will need to get permission from the owner of the copyright if you want to adapt it into a movie.

Contray to the previous post, it doesn't matter whether it's ameteur or professional - you still need to get the underlying rights sorted out if you want to show it to anyone other than your mum and your dog.

filmmaking.net

yea but i mean you can write a script without having to get premission. like i could write a script of friends if i wanted it just comes down to actually macking the film. for instance if you want to sell it to a production company you can write the script and let them worry about the copyright.

Make Love Not War!

A production company won't take a script that doesn't hold the rights to the story. They really don't want a lawsuit. You can write the script for yourself, but once you start showing it around you've violated the copyright law and could very well be sued. If you're going to use copyrighted material, you'll have to get written permission from the owners, which may very well require money. You could buy or option the rights as well, which happens with more professional stuff. So you can start writing the script now, but you can't do anything with it until you have the rights. So don't send it out to companies hoping they'll deal with it.