You get points when you pass the keydron through a gap. If you do a combo or trick as you go through a gap, you can get an even higher score.
In Normal and Endless modes, there are always two crystals in a gap. Touching both of these crystals at the same time with the keydron is called a combo. If you do a combo, you can get more points. Also, if you do continuous combos, a combo bonus occurs, and you can get an even better score.
Before going through the gap, if you rotate the keydron and pass over the gap with your keydron's shadow, a trick is achieved, and you can get a higher score.
Note that you don't have to cover the entire gap all at once with the keydron—the gap will almost always be larger than your keydron. Instead, you will often have to move and rotate the keydron multiple times to ensure that its shadow has passed over every part of the gap before the keydron slips through the gap.