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

While classical security with its best practices can be considered a science – fraud prevention is a kind of art. It is not generally possible to build a system which is 100% protected from frauds and cheats – but at least we can try, even when it requires us to cross the line and go into realm of the security-by-obscurity.

Fraud Prevention, page 1:

Payment Processing. Credit Cards. Chargebacks and Collateral Damage

Quote: “Chargeback monster will come from under the bed and will eat all your hard-earned money!”
Another Quote: “it is trivial to develop a system with guaranteed zero chargeback rate – to achieve this, it is sufficient to decline each and every transaction at pre-filter stage”

War on Clones, Part II. Identifying Mobile and Browsers. Social and Payment-Based Identification. Putting it all together.

Quote: “as much as iOS is a device identification nightmare, Android is a device identification paradise.”
Another Quote: “Everybody makes occasional mistakes, cheaters/abusers included.”

War on Clones, Part I. IP-based (non-)Identification. Identifying PCs and Macs

Quote: “NEVER EVER use IPv4 for long-term bans”
Another Quote: “If using MAC addresses to identify devices, you SHOULD gather stats on repeating MAC addresses within your DB”

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”

Chapter III. On Cheating, P2P, and [non-]Authoritative Servers from “D&D of MMOG” book

Abstract: “Any successful MMOG faces cheaters, and currently authoritative servers is the only way which enables fighting them.”
Quote: “Two things are infinite: the universe and human stupidity; and I’m not sure about the universe. — Albert Einstein”