Im not native speaker and have some difficulties with this question. As I remember, I saw "Which ... is?" statement in some grammar books. Is it correct?
Most native speakers would say, "What year was this game made?" or "When was this game released?"
"Which" is more technically correct, but few people are going to bother with being technically correct in everyday conversation.
I would ask the question in this manner:
In what year was this game released?
or (if appropriate):
In what year was this version of the game released?