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

This category consists of posts which form “1st beta” of the Vol.I-III of the upcoming book “Development & Deployment of Multiplayer Online Games”. Please note that “2nd beta” (available on Indiegogo) has 75% of the new content compared to the “1st beta” (in particular, based on the comments here on ithare.com and on /r/programming), so please don’t hit me too hard for the quality of the “1st beta”. ToC of “2nd beta”.

D&D of MOGs: Vol I-III (1st beta), page 2:

MMOG: World States and Reducing Traffic

Quote: “In practice, for most classical RPGs you can get away with simulating each of your PCs and NPCs as a box (parallelepiped), or as prism (say, hexagonal or octagonal one)”
Another Quote: “Mathematically speaking, without Interest Management, the amount of data on our servers will need to send (to all players combined), is O(N^2). Interest Management reduces this number to O(N)”

MMOG. RTT, Input Lag, and How to Mitigate Them

Quote: “For fast-paced games, there is one big problem with the flow shown on this diagram, and the name of the problem is “latency” (a.k.a. ‘input lag’)”
Another Quote: “No, better bandwidth doesn’t necessarily mean better latency”

MMOG Server-Side. Programming Languages

Quote: “From the 50’000-feet point of view, 90% of the differences between modern mainstream programming languages (as they’re normally used – or better to say, SHOULD be used – at application-level) are minor or superficial.”
Another Quote: “On the server side (unlike client-side) protection from bot writers is not an issue (as server-side code is never exposed to players)”

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”

MMOG Server-Side. Eternal Linux-vs-Windows Debate

Quote: “Each server is only as secure as its admin”
Another Quote: “For cheaper servers, the difference between Windows and Linux can eat as much as 50% of the server rental price (though for those servers which are more or less optimal price-performance-wise observed difference was closer to 20-30%).”

Server-Side Architecture. Front-End Servers and Client-Side Random Load Balancing

Quote: “[about Round-Robin DNS] one of these returned IPs can get cached by a Big Fat DNS server, and then get distributed to many thousands of clients”
Another Quote: “As a rule of thumb, Front-End Servers are a Good Thing™”

Server-Side MMO Architecture. Naïve, Web-Based, and Classical Deployment Architectures

Quote: “If you disrupt the game-event-currently-in-progress for more than 0.5-2 minutes, for almost-any synchronous multi-player game you won’t be able to get the same players back, and will need to rollback the game event anyway.”
Another Quote: “However, keep in mind, that all fall-tolerant solutions are complicated, costly, and for the games realm I generally consider them as an over-engineering (even by my standards).”