Announcements this week that “BioShock 2” (above) and PlayStation 3 exclusive “Heavy Rain” won’t be hitting stores this fall mean gamers who plan to pick up “Halo 3: ODST,” “Call of Duty: Modern Warfare 2,” “The Beatles: Rock Band,” “Brutal Legend,” “Assassin’s Creed 2,” “Left 4 Dead 2,” “Guitar Hero 5” or any other blockbusters scheduled for the fall just saw their purchasing decisions get a little simpler. But what does it mean for these two buzzworthy titles?

In the case of “Heavy Rain,” a thriller/mystery where you control four characters searching for a serial killer, the delay could be a good thing. It’s a brand new franchise from a publisher best known for a game called “Indigo Prophency” (“Farenheit outside the U.S.) While that game drew rave reviews when it debuted on the Xbox and PlayStation 2 in 2005, it didn’t exactly set sales charts ablaze. Another game from the same creative director and development house would probably be best off hitting stores in a relatively quiet time of the calendar year for new releases, rather than amidst heavily hyped games published by Activision, Microsoft, Electronic Arts and Ubisoft. What’s more, “Indigo Prophecy” caught a little bit of flack from reviewers for the second half of its story. Maybe a little more time in the hopper can help “Heavy Rain” avoid the same fate.

“BioShock 2,” however, is looking worrisome. After the critical and commercial success of “BioShock,” first on the Xbox 360 and PC, then on the PS3, the sequel was looking like a sure bet to be one of this fall’s biggest successes. But the potential for trouble has buzzed around the title.

To start with, “BioShock 2” is coming into the market as a sequel to a beloved game that had what felt like a pretty final, definitive ending. Like the first game, the sequel is set in the underwater city of Rapture, 10 years after the events of the first game. Because of the underwater, falling-apart nature of Rapture when we last visited it, setting another game within the city’s confines without reusing any of the first game’s landmark locales could be a tougher sell.

Additionally, 2K Games has put the sequel in the hands of four different development teams, none of which is Ken Levine’s Boston-based Irrational Games, aka 2K Boston, which developed the first “BioShock” with 2K Australia. This time out, 2K Australia is still involved, but the lead studio is 2K Marin, a Novato-based team that handed development on the PS3 version of “BioShock.” While many of 2K Marin’s employees worked on the first “BioShock,” swapping out the creative director of the game is akin to changing a lead writer in a movie franchise: Often it works out fine, but it represents a risk nonetheless. 2K Marin will be assisted on the title by Digital Extremes, a Canadian studio that’s handling a multiplayer component of the game, another creative risk. (“The first “BioShock” had no online multiplayer at all.) What’s more the announcement this week that the game would be delayed until next year came just a couple of days after a fourth studio, France’s Arkane Studios, would be assisting with art, design and animation.

With four studios each working on a different part of the game, the creation of a multiplayer component where there once was none, the loss of Levine to another project and the various narrative challenges posed by the constraints imposed by the underwater setting and the first game’s narrative and you’ve got a lot of moving parts to keep track of. For someone who absolutely loved the first “BioShock,” it can be a bit troubling to read that the game is being delayed until 2010 for quality-related reasons.

On the other hand, though, plenty of games get delayed for similar reasons, only to emerge just fine. Two 2K-published titles I can think of that suffered similar fates were “Grand Theft Auto IV” and “The Elder Scrolls IV: Oblivion.” (“The Lost and Damned,” the first downloadable add-on for “GTA IV,” was also the subject of delays.) It’s clear that 2K, which operates on a tier of game publishers just outside the orbit of Activision and Electronic Arts wants to do right by its franchises. Hopefully the myriad cooks in “BioShock 2’s” kitchen can still turn out a masterpiece.