Not sure if they're being serious, but there's what looks like a "3" on a distant air-con unit, next to left-most tree. If your viewport is narrow you might not see it [0]
Unless GP would care to point out what you're supposed to be looking for, I think you're being trolled into poring over the image looking for something that isn't there.
“It” wasn’t pointed out at all in the original post. Just “look on the far left” with no indication of what.
I’m not convinced this 3/E means anything. If they’re making HL3 or HL2:Ep3 then we’ll find out soon enough. Many people have tried to read the tea leaves by scouring textures and images in GTA V over the years, and every time they’ve been made to look stupid. If there’s an announcement to be made around HL, Valve won’t hide it in a Steam sale banner
That happens to games all the time. This is one very unique grudge to hold. I'd be happy that Alyx happened at all. Valve could never live up to expectations for Episode 3 / Half Life 3 anyway.
You missed the joke. It's been so long now since HL2 that the joke is to find any implication of "3" (or even work back to three via vague associations between random things) and say "HL3 Confirmed!".
[0] https://cdn.akamai.steamstatic.com/steam/clusters/sale_autum...