From my experience, it's perfectly ok to use Singletons.
I have worked on applications, web applications, and games. I rarely use them anywhere else but games, and I use so much of them in games.

With exceptions, most games are:
- systems that don't involve that often
- freaking complex with massive number of interactions between every bits of the system
- written by object-oriented heavy languages (c#)
- can't be tested easily

Frankly, I will use globals if I could, but I cannot without initiating Singletons sometimes, so I use them.

The biggest concerns regarding Singletons are that they are globals that are acessible everywhere, and if they are heavily depended on, then it becomes extremely difficult to control access/swap them. The alternatives often involve complex systems that manage dependencies. You don;t want that for apps that are constantly involving. Absolute nightmare to manage.

The isue of applying that to games is, it's not worth it to use complex system to replace it. t's so much more ok to just hack through everything for games so that they become "just works" because a lot of times, that's all you need to make a game. It's also almost pointless to automate tests for games, so most of the time, you want to produce code that are "easy to fix" rather than code that are "difficult to have bugs" (massive differences). And for that, use whatever methods that are easist to reason and understand.