Firewatch and No Man's Sky have been the year's biggest hyped games, with Stardew Valley and Enter the Gungeon the biggest surprises, if some figures turned out by Steam Spy are taken at face value.
It's important to understand what Steam Spy, the web tool that analyzes publicly available data from Steam, is presenting here: It's a game's concurrent users on its launch day, and then the concurrent users two weeks later. A big drop-off equals hype; a big surge is a surprise.
SteamSpy's creator, Sergey Galyonkin, said he was asked by a Twitter follower to derive "hype" and "surprise" using these measures. RWBY: Grimm Eclipse, the hack-n-slash game based on the Rooster Teeth series of the same name, came in first with a "hype factor" greater than 10.5. Next was Firewatch, No Man's Sky, The Walking Dead: Michonne, and Mighty No. 9. The top 15 are in the tweet below.
Galyonkin himself says he doesn't think this is "a viable metric, as some games are short enough and hyped enough to be bought and completed in mere hours." Firewatch, by design, doesn't have much replayability once a player completes the story, which does not take two weeks, that's for sure. The Walking Dead: Michonne and Hitman also are episodic games where users, particularly in Michonne's case, may be snarfing down everything in the first two weeks and waiting for the next installment.
As for surprises, or slow burns, Galyonkin worked in the other direction to see which games had small launches but much bigger populations two weeks later. Romance of the Three Kingdoms 13, a strategy title from Koei Tecmo, took top honors. Stardew Valley is fourth, but notably had the most day one concurrent users among the top 15, and the most two weeks later (naturally). The full 15 can be seen in this tweet.
The reverse metic should be called "Surprise Factor" for the games that grew the most after the release :) pic.twitter.com/VVxG7bG8Vb— Steam Spy (@Steam_Spy) August 27, 2016
So what does this say? It's not an expression of game quality, just game attention, and it can trail off or accelerate for plenty of reasons unrelated to appeal or sales. If there is a trend though, it's that the hype list is littered with the kinds of big names we and others typically cover pre-launch, and the surprise list features smaller or much lesser known titles. Also, the quality of the surprise (that is, the factor expressed as a number) is smaller than that of the hype.