If you're looking to fill out your backlog and you've somehow managed to avoid the dozens of sales that happened during these past few weeks, you're in luck as a brand new Steam sale is just around the corner. According to SteamDB who have managed to get their information through Steam Direct, the next Steam sale will run from February 15th to 19th in order to coincide with the Lunar New Year festivities.
Naturally, none of this has been officially confirmed just yet, but SteamDB has been pretty damn accurate in the past, so given that their source is Steam itself odds are they are going to be correct on this one as well. Besides, it makes a lot of sense for Valve to release a massive sale during a holiday where it's customary for people to give children and young adults money.
As for which games will be on the sale, that I'm afraid nobody knows. Chances are there will be a lot of Asian games to peruse through, though I would imagine a lot of western games will not skip the opportunity either. So if you're planning to grab some of 2017's hits like Resident Evil 7 or NieR: Automata, it's probably a good idea to wait until February 15th as you're likely to get them a decent discount.
If you don't feel like waiting, however, you might want to check out the currently ongoing sale over at Humble Bundle. Just don't dilly-dally for too long as it's going to conclude tomorrow, January 25th.