Original Unreal Tournament is a pretty good one for this, I copied the install to a thumb drive on high school and played it on school computers all the time. Same with GZDoom
@inbounds isn't the problem, it's incorrect usage of it. The poor docstring is absolutely a problem though, you should be iterating over eachindex(A), not 1:length(A).
Dispatch ambiguity can really bite you, particularly if you start extending methods from other packages. An issue I often run into at the same time as method ambiguity is a stack overflow from self-calling constructors. If you try to define an outer constructor with default arguments, it's really easy to end up just calling that constructor from itself.
The metaprogramming trick for defining a set of methods at once is useful, but I wish there were a more compiler-level solution to sorting out ambiguities or determining what's more "specialized".
These don't really color my view on multiple dispatch, however. I find it to be a really useful tool and I don't run into dispatch issues very frequently. If you're meticulous about your typing it's usually easy to avoid these pitfalls, but sometimes they still crop up.