Could Half-Life 2: Lost Coast count?

I dunno.
I usually never skip beach episodes in anime, they feel weirdly integral to a show despite being the most baseline version of filler. That's my feeling on these games too, which is why it would be a no, but I'm open to alternative viewpoints)

Then maybe Half-Life 2 episode 1 does. It continues the plot of the base game and adds a new enemy as well as some interesting setpieces, but it's short and rather uneventful (Gordon and Alyx get back into the citadel, stabilize it, run away, oh no everything is exploding, cliffhanger ending). It's fine while you're playing it, it's more Half Life 2; compared to even just Episode 2 though, which furthers the story meaningfully and adds a wealth of content (new locations, vehicle section, bosses, enemy types and amazing, memorable setpieces) Episode 1 can't help but feel rather filler-y. This might still not be it, it's even technically an expansion, but I had to try since Half-Life has been stuck in my head for the better part of a year now

But it's called Episode 1, so it counts