(what has it been? like, a year??)
the full changelog is here: 
https://mysteriousspace.com/changelog/0-10-x/ but here's a summary:
I switched from DirectX to OpenGL. this allows the game to support generic gamepads (not just XBox 360-compatible), and up to 16 of them. DirectX limited us to 4, which meant Mysterious Space could only do up to 5 players (4 gamepads + keyboard); now Mysterious Space supports up to 8!
I also took the opportunity to tackle a couple gross bugs…
- the lag that some players had been experiencing while playing the game fullscreen should now be fixed
 - when playing co-op and staying near each other, enemies will no longer spawn in the middle of each other's screens. (this does not fix beehives and the little black gnat things, which will sometimes spawn directly in view for other reasons >_>)
 
… add some new content…
- a new type of planet: Crystal planets!
 - a smattering of new graphics
 - a new request that outposts may have for you
 - a new Advanced Technology effect
 
… and get in a few quality-of-life improvements:
- UI for when a gamepad is disconnected during play, allowing you to reconnect or assign a new gamepad
 - customizable keybindings for directional keys
 - the mouse can now be used in some areas of the game (but not during play)
 - slightly-improved French translation, and improved support for translations in general (although there's still a bit to go…)
 
I have several other things I'd like to add to Mysterious Space - including smallish things like hazardous meteor swarms, and larger things, like an entirely new co-op mode - but I hesitate to make any promises about when such things might get released. hopefully in less than one year, anyway :P
have fun, and thanks for playing :)