Look at the backglass. There are three verisions:
1. No stars - the original one.
2. Small stars - barely cover the offending artwork (exposed breasts, crotch grab, etc)
3. Big stars - covers the offending artwork.
No stars - most valuable, price goes up.
Small stars - more valuable, price goes up a little.
Big stars - least valuable, price goes down a little - very common.
It's a popular game, fun to play. No stars / small stars, in very good shape, up to $2500.