Say I'm looking for a certain kind of third-party library/framework/engine to fill some role in my game. I find a library that fits my requirements, or at the very least fits my requirements better than similar libraries. The only drawback is that the project is apparently dead. The web site hasn't been updated in years, the forums are empty, and the source repository seems inactive.
The library is open source, so it's not necessarily lost. But then I'd have the responsibility of maintaining the library myself in my own project. The alternatives are (a) using a worse but active library or (b) implementing the library functionality myself and possibly killing my project again.
How do people here feel about using libraries that aren't maintained by anyone anymore? Does it ever depend on the project and/or what the library does?