Just played two games in a row with the same pattern. Cheater 1 builds up, Cheater 2 provides a buffer while building up himself. Borders left unsecured. Once a non-cheater gets cards and poses a remote threat, the cheaters go for him, taking turns until he's eliminated.
The attack patter would make no sense to the neutral observer, but the cheaters don't even care. Between that and the AI bias, this game has been ruined.
When I initially joined Risk, I worked my way up to Expert, then was knocked down to Novice by cheating. Recently made my way back up to Intermediate, seems I went a short time without running into many suicide attackers, but was then quickly knocked back down to Novice again, by both cheating and the AI attacking in a way an actual player intending to try to win never would.
I have gotten to the point where if my opponents are weak, but instead of joining the other, one attacks the other and not me, I wipe him out first, even though he was doing me a favor. Obviously, in this case it wasn't cheating, but the behavior brings to mind the cheaters and all the time and effort they cost me, so I destroy them first. Now I find that coming in second in the game helps your score, which is probably why Grandmasters are constantly allied with Masters (because they're the same cheaters, I mean person, just one of their accounts is selected to always comes in second, hence the slightly lower rank), so I am pleased to wipe out irrational players sooner than honest strategists.
Oh, and I just played a game where early on I left Normandy undefended, and made an alliance with England. But I doubt people would be suspicious of that, because the troop levels I had in Flanders and Provence would have been overwhelming. The troops he had in Southern England would have been enough to weaken me to the point that I would have been vulnerable to an Ottoman attack. I never even had to betray him/her because he got wiped out by a joint Ottoman/Russian attack.
Interestingly, I also won a game earlier where many people, looking at my strategic situation, would say I was toast, and I would have agreed. I was hanging on by my fingernails. I controlled Russia, and the Ottomans took the Austrian Empire as well as capturing Belarus and Minsk from me, and I did not have more than two troops on any territory I had left. But the Ottomans had left a gap and I siezed Slovakia, Hungary and Serbia.The player who controlled the British and the French Empires took the opportunity to attack the Ottomans, who counterattacked and damaged him badly, and by balancing the two players I ended up the winner.
The Lesson: Players who stop trying because it seems hopeless don't understand the game, or life, or the world.