What is the fine-grained topic of the following text: While THQ execs wouldn't put a dollar figure on the answer, one of them called the price to get the game to the PS3 "a fraction" of the original development cost, saying 15 percent was "not a bad guesstimate" on the cost of porting an Xbox 360 game to the PS3, or vice versa. Only return the topic.
Cost of porting games between Xbox 360 and PS3