Never seen the whole thing? Don't worry, I didn't ruin it for you. See it. It was done with a very low budget by a bunch of unknown folks about 30 years ago.
In my video game version of this film, the player is in control of the beast in the basket, Belial. Here he is sitting on some steps...
You drag yourself around 1982 Manhattan, while your once-conjoined brother, Duane looks for you. He'll put you back in the basket. You don't want to be in the basket. Got it?
Through a series of challenges, you must figure out unique ways to enter buildings and use human devices (phone, electric razor, fishing pole) seeing as that you don't have all the normal appendages and digits us regular folk have. You're finally on your own and want to show Duane you don't need him. You must eat humans when you're hungry or if they threaten you in any way. If Duane locates you, you might be faced with the chilling notion of attacking and eating him. Or just part of him. You're pretty darn good at lying low, so I suggest waiting under chairs and beds for the right time to attack. Can you drive? Maybe. Try not to attract attention to yourself and give it a whirl. Want to explore the seedy Times Square theaters of early 80s New York? Go ahead. You, might want to wear a poncho, though. Horseback riding through Central Park? Not impossible. Quite fun, actually. You're free. Enjoy life and all it's mysterious foibles.
This game would follow the third-person shooter format, with a choice of various viewpoints to better enable you to see what the heck's going on above everybody's knees.