I honestly have no idea how Lumini [official site] ended up on my PC but last night I found it in my "Oddities" folder alongside a number of other alpha, pre-alpha and demo bits and bobs. It turned out to be a restful flying fish experience - a hint of a puzzler-to-be pervaded but mostly I just enjoyed the exploration and movement.
Lumini are a little shoal of fish-like creatures, although their flappy side fins make them look more like fishbirds. According to developers, Speelbaars, you need to protect and evolve them to ensure the survival of their species. By collecting little motes of light and depositing them at crystal collection points you get to bolster or restock the shoal. That's useful because if you swim into anything red - spiky crystalline surfaces, porcupine-y sea slugs, weird fungal flowers that spit spores - it can kill off some of your Lumini.
There's some protection, though. Bashing into vulnerable spots on prey with the power of the shoal means you'll kill them (or perhaps knock them unconscious) and thus the next lot of sparkles you hand in will offer different types of Lumini. Red ones give you a kind of forcefield round the nose of the shoal when you press RT and help with bashing into foes while the greeny-blue Lumini give you a little speed burst.
Another neat thing is how you can split the shoal to solve little gate puzzles. On a gamepad that's done by using the right stick to take separate control of half the fish while the rest stay under left stick control. With two teams you can activate two switches at the same time or hold a gateway open so the other half of the shoal can pass through and do the same for the first lot from the other side.
I've had a soft spot for one player controlling two separate units since a PS2 game called Kuri Kuri Mix where you faced along timed courses as two rabbits working together, then there was Brothers far more recently. From what's in this pre-alpha I hope Lumini develops those ideas into some cool challenges, but I'm also finding I'm content to simply whoosh around in the space, pirouetting between cranky fish and reorganising my shoal by colour.
The demo is a pre-alpha version and is about a year old now, I think. It's buggy and sometimes my shoal would get stuck on rocks or the controls would become unresponsive but if you are in the mood for something restful and haven't encountered Lumini on your travels I'd say it's well worth dipping a toe in that water before the full game releases in the next few months.