Changelog for update 1.455 / GOG-8 (Windows) / GOG-6 (Linux) / GOG-12 (Mac) (added 03.09.2015):

- Added "No Vsync" option
- Improved collision detection w/powerups
- Added selectable controller profiles, and slightly better controller detection, as well as a "reset" option.
- Added input reset hotkey: Hold C on main menu for 3 seconds.
- Powerups should now spawn more consistently between rounds
- Fixed glitch when sun goes down while holding a shield
- Fixed bugs where powerups from portal would still be present in main world
- Fixed achievement bug where certain achievements showed progress incorrectly
- Fix for rare crash when entering portal
- Upgraded Unity engine to 5.1.3, which should bring some performance improvements in Linux, potentially fix some rare crashes, etc.

Patch 1.453:

- Fixed "Error Calculating Rank" bug (for real!)
- Mac builds are now 64-bit.
- Fixed level editor lockup when using "test" button
- Can now create more than 25 levels in editor
- Improved Level Editor screen user experience
- Fixed engine sound for first-person mode
- First person setting will now persist for game session duration
- Fixed some issues with some portal worlds causing lock-ups

...and now it doesn't launch.

I just played it two days ago, after updating there's a brief pause after clicking play in Galaxy and then nothing, when accessing the game directly there's not even that.

Even trying to run it from the command prompt gives no errors, just nothing at all.

Changelog for patch 1.50 / GOG-9 (Windows) / GOG-17 (Mac) / GOG-7 (Linux) (added 02 February 2017):

- several Portal Worlds addded
- online backend compatibility fixes

Changelog for patch 1.51 / GOG-10 (Windows) / GOG-18 (Mac) / GOG-8 (Linux) (added 13 February 2017):

- Minor gameplay bug fix

Edit: I got ninja'd