so I played gravity swap! very nice, reminded me a lot of Terry Cavanagh's VVVVVV, with a little bit of Thomas was alone. The graphics were nice and the trail effect on the character was pretty cool- as was the gravity swap particle effect- it was nice to have that visual feedback.
There was a few things I would tweak slightly- the hitbox was a little too large on the spikes- there was a few times when my character 'hit' the spikes without actually touching the sprite (normally around the corners) which got a little frustrating. I also found the gravity value to be a fraction low, so the character felt quiet floaty. left-right movement was quite snappy though, so that was nice. the visual language of the obstacles was a little iffy- the first level I came to the rotating knife/disk things I tried to 'collect' them because I thought they were stars. A solution would be to maybe make all things that can hurt you a distinctive colour- red, or pink maybe- then the player thinks "if the spikes are red, and kill me, and this thing is *also* red, it will probably kill me too".
I enjoyed it though, well done!