Unearth by William Bowerman
Your goal in Unearth is to dig, or should I say unearth the very ground at your feet, until your little mining dude has spelunked as deep as he is physically able. What separates this subterranean platformer from Dig Dug, Spelunker, Spelunky and the like is the presence of a precious stamina bar, which whittles down with every exhausting movement. You therefore need to plan each of your moves in advance in this fun, puzzley platformer, which features a trio of difficulty levels, and piles of snakes.
Harry Houdini and the Mummified Meanies by Neil Makes Games
This extremely simple but extremely accomplished sidescrolling platformer puts you in the role of famed escapologist and, I guess, big ol' tomb robber Harry Houdini (drawing on the H.P. Lovecraft story Imprisoned with the Pharoahs). While avoiding spikes, ghosts, mummies and nasty bats, can you single-handedly plunder an entire pyramid of its gold reserves? Yes, probably, as this isn't very difficult, but it is bloomin' charming, while the era-appropriate music fits like the proverbial glove.
Late Night Wanderer by Darryl Long, Nick Duxbury, Tristan Shaw, CheukNam Wong
Late Night Wanderer aims to recapture the feeling of walking alone, late at night, in the city, and I'd say it's pretty darned successful at that. Its dimly lit, sporadically spooky world invites you onward with distant lights, before muddling your sense of direction via obfuscating architecture. Your only friend in the city is your mobile phone, which will occasionally buzz thanks to text messages from your friend, and which will light your way (in a bit of a rubbish and limited way) with its in-built torch. The battery is nearly empty, however, so if you're to have enough juice to make it home, be sure to only check your phone when it's absolutely necessary.
Aria's Story by Lydia, MeruM SB, Kaliblu, AdamCha
A cute and creepy top-down adventure set in an enormous library. This huge book repository is ordinarily one of your very favourite places, given how much time you spend in there with your nose buried in a tome, but the place feels very different one day when you fall asleep and wake up, on your own, in the flaming dark. Mild spookiness awaits in Aria's Story after that, which will be familiar if you've played other, similarly themed RPG Maker games.
darkfore.st by Leonhard Storm
A huge, ambitious sci-fi sandbox with only a couple of teeny tiny caveats. It's purely text-based, for one thing, so be prepared to reach for your reading specs. The other caveat concerns the game's moderately baffling interface. I haven't delved too far into it yet, but if you can handle Dwarf Fortress, and you appreciate good writing and novel approaches to familiar territory, I reckon you should make some time to venture into the darkfore.st.
It's possibly the only science fiction game (at least that I've come across) that features both galactic expansion and a rigorous adherence to the laws of physics, meaning no faster-than-light shenanigans to allow you to cross the sea of stars in a matter of moments. As the website puts it, the hard speed limit "makes not only space colonisation, but also assessing the strength of other civilisations extremely difficult. An unbreakable speed limit transforms the universe into a terrifyingly dark and inscrutable forest, with no telling whether the next predator is already on it's way to you or how strong that predator is going to be." Crikey.