It's making a list, it's checking it twice - Valve's figuring out who's naughty or nice. And it seems to be working, as the company cleared out over 600,000 misbehaving Steam players in December.
The spike in Valve Anti-Cheat (VAC) bans was spotted by Nors3 on Twitter (via PCGamesN), and aligns with the figure of 609,375 seen on SteamDB. In contrast, the number of VAC bans handed out in November was significantly lower, resting at a moderate 103,744 bans.
As Nors3 highlights, the likely culprit is CS:GO, which coincidentally went free to play and got a battle royale mode in December. This brought an influx of new players, and probably encouraged more cheating by removing the financial risk of getting an account banned. Those pesky battle royale kids, eh?
VAC is Valve's automated anti-cheat system which detects cheats installed on PCs and (in theory) immediately bans misbehaving players - although somehow this never seemed to stop TF2 aimbotters. It's a cat-and-mouse game for Valve, which has to figure out the latest cheating methods and prepare measures to defend against them.
CS:GO may well have sparked the increase in numbers, but it's likely Valve's other free to play titles - such as TF2 and Dota 2 - also had a role to play in the record-breaking month. Many CS:GO players, however, are still highlighting problems with bots (such as this amusing team-killing one) - so it seems there's still more progress to be made on rooting these out. Or maybe the bots will just kill each other first.