Everyone always references Minecraft, but that's not the only
Java game out there. There are quite a few on Steam. You'll never
even know they're Java if you don't follow their development, as
they ship with a bundled JRE. The Java games that perform poorly
or hog resources are always held up as an example of why Java is
a dog or why GC for games is a problem, but then the ones that
perform well don't even become part of the conversation.
Experienced Java game developers know how to code to the GC and
tune their apps to maximize performance. There's quite a lot of
knowledge tucked away in the posts at java-gaming.org, where
they've shared their experience and their games. The GC itself is
not a deal breaker, nor is the Java language. People prove it
every day.
The same can be true of D. When enough D experience has been
accumulated and shared, people will be writing games that take
the GC into account. There's no reason to avoid it completely. It
can be made to work for you. Even today, games in C and C++ focus
on minimizing allocations, using the stack as much as possible
and setting aside as much heap memory up front as they can. Given
that collections in D only run during allocations, there's no
reason why that same strategy won't work in D. It's all about
strategy and profiling, finding what hurts performance and
learning how to avoid it.
