Sizeable lag between pressing space and actually jumping makes the game frustrating to play.

It's a bit difficult to get the timing right on some levels, and the challenge of figuring out how to get the crystals is a bit tedious, It's not inherently a bad game. However, I feel if it were refined more as a concept it could be a lot better.

I use Opera browser, and Ctrl + Space opens the search tab by default. (imo, all system keys: ctrl, shift, alt, should be discouraged in games.)
The first level was confusing as I searched for the controls... Other than that, game seems nice.