Knossu by Jonathan Whiting
Whiting describes Knossu is a "non-euclidean horror game", a Lovecraftian term that tends to describe geometrically weird places—and so this is. It's a game about exploring a tricksy maze that loops back on itself, that warps you around with apparent abandon, that feels expansive and claustrophobic at the same time. I desperately want to talk about this labyrinth's innovative monster, but I don't want to spoil the monster—so I'll just implore you again to play Knossu immediately. Man.
Treasure Hunter Man 2 by origamihero
A Metroidvania about a mother searching for her teenage son. Like most mothers searching for their teenage children, she battles monsters, destroys blocks, and evades spikes as she explores a lovely desert island. It's like a fast-paced, smaller Treasure Adventure Game, this, not quite as good but then few exploratory platformers are.
Capsule II by PaperBlurt
I've not played the first Capsule, but I don't feel like I missed anything in playing PaperBlurt's funny, dark and gripping sci-fi sequel. You're a cryogenically unfrozen caretaker, aboard an ark carrying humanity through a handy space-hole, and you first have to contend with your own boredom, then your own madness, then...well, I'm not going to spoil this one either. But it's a bit horrific.
Sonam in the Storm by James Shasha
A very short piece of interactive fiction that's quite enormously overwritten, but that hints at an interesting diversion for IF. Sonam uses UnityTwine to, um, install Twine in Unity, and the result is nothing short of beautiful. It feels pretty weird to click on hyperlinks in a 3D space, but it works with the game's lovely low-poly background, and with the The American Dollar's soundtrack, to create an IF of great atmosphere.
They Came from the Roof by Kodained
An eminently playable arcade-style game that mashes up Pac-Man, Mario Bros, Space Invaders, Breakout, and probably some other games I didn't recognise. And it works. Hooray! As one or two players, you're trying to protect the ghosts from Pac-Man—which essentially act as your extra lives—by shooting monsters before they climb down to their hidey-hole.
This gets more difficult in later stages, as the number and speed of enemies increases, but your main opponent is the big Breakout paddle that seeks out and blocks many of your bullets. You'll need to team up—the AI is surprisingly good in single-player—with one player distracting the evil Breakout block, giving the other's shots a chance to get through. Marvellous stuff.