-make sure your track is wide at the beginning an gradually gets narrower ( like 2/3 of the starting track)
-add a cool and entertaining winning event at the end (like in hydro plant it explodes)
-make sure you have shortcuts that are harder to navigate but aren't impossible
-add treasure chests even though barely anyone gets them all.
-keep in mind for hazards, theme, background scenery, and most importantly that the track doesn't gradually lower and overlap itself (like a bridge at the start of a track but you can just jump off the bridge to get to a further part of the track)