The Trolley by _memex_
Lament a closed transportation system in the stylish The Trolley, which mixes first-person exploration with a diverging story that takes place in your head. As you explore this wistful, strangely untextured and interestingly fictional world, you'll think back to the trolley's heyday, and ruminate on your own feelings about how and why the system was shut down.
Antbassador by Kevin Zuhn
You play as a human ambassador making an important visit to the ant community in the deliciously titled Antbassador, an only moderately infuriating physics game where you play as a big human hand. It's a bit of a shame that it reloads to an earlier checkpoint when you accidentally, and inevitably squash one or more ants with your ginormous finger here (it might have been funnier to see the game run with your mistakes), but there's a lot of humour, and a few tricky physics situations in this small game with a tremendously fun premise.
Sketch What You See by Jade Smith
Contrary to the name, you're not going to be doing any sketching in Jade Smith's Sketch What You See, which is instead a relaxing puzzle game with a clever central mechanic. You're trying to match locations in the beautifully low poly environment to sketches scribbled in your Grandma's sketchbook, and to say any more than that would ruin the lovely surprise.
Storyseeker by Miles
Explore a peaceful (AKA combat-free) world in the thoroughly laid-back Storyseeker, which has you scrounging narrative by wandering here and there. In an attractive, diverse environment that reminds me a little of the Knytt series, you'll encounter, and occasionally chat to strange creatures, learning snippets of backstory that bring this minimalist place to life.
The Shroom Project by Hello Fangaming
What if the Mushroom Kingdom experienced a zombie apocalypse, and the only way to fend it off was to give Toad a gatling gun, a rocket launcher, and other devastating weaponry? It would likely be terrible, the most misguided Mario ever made, but I love the silly, off-message, and surprisingly fully-featured nature of indie fangame The Shroom Project. It's chock-full of blood and guns, like Mario definitely isn't, but it's one of the very few games to let you explode Luigi into chunks of viscera, which is certainly a novel experience.