If you're in trouble and cannot find an answer to a question which goes beyond Stack Overflow...
If you have a not-so-usual solution for your problems but need to justify it to your boss...
If you like to think on your own rather than blindly follow "common wisdom" and "profound truth"...
...then 'No Bugs' Hare on Soft.ware might be the right place for you.
Your mileage may vary. Batteries not included

TBH, I am a big fan of actor- and reactor-like programming patterns (also known as Finite State Machines. While you’re not strictly required to use reactors and might be able to get away without them – they DO provide several very substantial benefits.

(Re)Actors, page 2:

Ultimate DB Heresy: Single Modifying DB Connection. Part I. Performance (Part II. Scalability to follow)

Quote: “Dealing with transaction isolation is very far from being a picnic”
Another Quote: “One of such real-world systems was consistently processing over 30M real-world write transactions/day over one single DB connection, supporting ~100K simultaneous players.”

Deterministic Components for Distributed Systems

Quote: “Then you can recover from any single server failure in a perfectly transparent manner”
Another Quote: “after the program fails in production, we can get the input log and run it in the comfort of a developer’s machine, under a debugger, as many times as we want, and get exactly the same variables at exactly the same points as happened in production”

Implementing Queues for Event-Driven Programs

Quote: “full queues SHOULD NOT happen during normal operation”
Another Quote: “With queues-implemented-over-mutexes like the ones we’ve written above, the most annoying thing performance-wise is that there is a chance that the OS’s scheduler can force the preemptive context switch right when the thread-being-preempted-is-owning-our-mutex.”

Avoiding Ugly Afterthoughts. Part a. From Writing for Cross-Platform, to Writing for Debugging and Production Post-Mortem, with Error Handling in between

Quote: “It is strongly recommended to have your build server to compile your game for at least two sufficiently-different platforms from the very beginning”
Another Quote: “If allocation of 50 bytes causes an “out of memory” error, we’re probably already long dead because of unacceptable swapping. And even if we disabled swap file – chances that we will recover from this condition, are infinitesimally small”

On Zero-Side-Effect Interactive Programming, Actors, and FSMs

Abstract: “WHY are functional programming languages not popular for interactive programming purposes?” and “WHAT we can do about it?”
Quote: “IMNSHO, deterministic Actors are the very best thing in existence for interactive programming, with lots of very practical benefits (from production post-mortem, to protection of in-memory state against server faults).”

Unity 5 vs UE4 vs Photon vs DIY for MMO

Quote: “You can still use HLAPI despite its shortcomings”
Another Quote: “If you’re using one of the engines above (and not your own one), and your game requires Client-Driven Development Flow, you may want to start with a single-player Unity 5, or with a single-player UE4.”

Asynchronous Processing for Finite State Machines/Actors: from plain event processing to Futures (with OO and Lambda Call Pyramids in between)

Quote: “With ‘callback pyramid’ it is not easy to express the concept of ‘wait for more than one thing to complete’ , which leads to unnecessary sequencing, adding to latencies (which may or may not be a problem for your purposes, but still a thing to keep in mind).”
Another Quote: “Don’t even think of converting all of your code to a so-called Continuation-Passing-Style”