If it's a big name game, they may want them... regardless of how they attempt to get them.
IMHO since you don't have intentions to develop them into fan sites, DEFINITELY don't park them or try to make money off them. You might get away with selling them, but you are still at risk if they attempt to udrp or sue. The buyer is potentially liable as well if he doesn't use them appropriately.
If they were mine, I would either dev them into fan sites or try to contact the company and see if they want them for the reg fee, that you had plans to develop as fan sites, but no longer have the time, and wanted to know if they wanted them.
Just my opinion...
Totally agree with flamewalker here,.
Since you regged them to stop a domain shark getting them it's kind of bad faith,.
You need to develop these sites into something, do not park them,.
Since you have the names, try and get something on the sites, or drop them, but dont park them..
My friend, you have become what you feared.
To prevent a domain shark to get the domains, you become a domain shark good job.
Seriously just put a simple front page up, with only these text (or similar):.
"This is a fan site for (thenameofthegame). It is still under development. I can be contacted at (youremail)".
But as flamewalker and evertonian7uk wrote, please DO NOT park them, just put a simple page up with only the words, nothing else.
Personally, I would stay away from adding contact information. If you are developing a site, why would you want people to contact you? The reason I would think someone puts up contact information is to sell the domain (yea, I'm cynical, but usually my instincts are right on ). What may be better is put up a forum, this shows you are actively dtrying to develope the site and creating communication with other "fans"...
I agree with DNQuest his suggestion sounds a lot better then mine.