Not bad. The flying and surfing mechanics are nice and it gradually makes you do both movement with keyboard and action with mouse at the same time (no controller support). I think it took me somewhat over 3 hours and I didn't get all of the optional items (I'm usually slower than most people as well). I also don't think I found the secret bonus level.

It isn't one of my top favorites but as someone who likes platformers I found it more fun than most of the games I've tried here. At $3 it is a great value and I would love to see more games like this. It most reminds me of Little Bug and of the two I like Little Bug better, but I'm happy to have played both. Hopefully we will get more from this developer.

One thing I didn't like is that you can't go back all that far or replay just parts of the game, so if you are aiming for 100% and go the wrong way and activate a checkpoint, you may need to replay the whole game to get to that point again. My other main complaint is that there is a short pause before flying is possible when restoring from checkpoints but sideways movement is still possible leading to quick deaths. The music and story are both minimal.

Since achievements were mentioned (and the stray text is still there on the store page), I'll say there are no achievements in the standalone version. Personally I find them annoying and turn them off when possible anyway. It is possible they might be in the galaxy version but it isn't mentioned under features so I would guess not.

I played this game somewhat soon after Trine was on Humble Bundle. I remember Nyx as very similar to Trine in many areas, yes still making something new. Looking at pictures today its sure looks little...simplistic in terms of design and picture, but it was pleasant experience back then.
That amaze me is how long it taken to get it on GOG.

Is there any way to use a controller with this game? I use a gaming keyboard + mouse (both from Redragon), but I'd think this game would be easier to control with a gamepad; mine is a Xbox/Windows compatible pdp afterglow model.

I haven't tried it but joytokey should work or another similar utility. The one catch is that the flying mechanic limits wing flaps to five and the usual movement controls on most gamepads (including yours it looks like) do not fully seperate the directions. If you want to use the left stick for movement then maybe L for flying and LT for gliding and right stick for mouse movement and R for mouse button. Or another option might be A for left, B for right, Y for flying, R for glide, L for left mouse button, and the left stick for mouse movement.

You're wrong. There are a lot of puzzles in the game, where you control the character with one hand (keyboard) and at the same time move or manipulate objects on the screen with the other hand (mouse).
And if in terms of character control everything is real from the gamepad, then the second part cannot be adequately reproduced due to insufficient control accuracy (On mobile platforms, this is solved by using a touchscreen).