They are one of a kind, but they aren't without alternative ... because they are luxury not necessity. A one of a kind software project meant to run a factory is generally without alternative.
Maybe for factory automation you have no real choice, which I'll admit I don't know much about. But in other areas you'll have, say, HP, IBM and Oracle all trying to get a contract for a solution/project. Meanwhile, for games, I don't think the games are entirely fungible, not for big names. Someone in the market for Metal Gear Solid won't go for Call of Duty. They may not even go for something closer, like Splinter Cell.
Areas of software development which are not commodity can't really be compared to games. If we take the grand daddy of commodity software development, Microsoft, slips are once again pretty common.
Vista's development was very troubled, but isn't Office actually pretty good at staying on schedule? Visual Studio too?