If you ask me the easiest form of jumping is the mouse, but I like how the developer used four different keys to jump so we could use what was best for us.
It really only gets somewhat challenging on the last level, the components for a good game are all there but you didn't pull it together. But if you're looking to make the game better I would suggest an "endless mode" Where the gems fall in intervals of time and you have to clear them before they reach the top.
It's a really good game, but I do suggest cutting off some time from the cutscene where you see your rank, I think it's a tad bit to long. But other than that a good game, with nice music and a diverse skill tree.
 "Frantic Frigates"){kind=icon}
 "Nightmare Runner"){kind=icon}
 "Move Gems"){kind=icon}
 "BeautifulFarm"){kind=icon}
 "Cowlorful"){kind=icon}
 "Wake Up the Box 4"){kind=icon}
 "Attitude"){kind=icon}
 "Nuclear Justice 2084"){kind=icon}
 "Cascade"){kind=icon}
 "1928"){kind=icon}
 "Tower of Heaven"){kind=icon}
 "The Final Death Wish"){kind=icon}
 "Idle Dancing"){kind=icon}
 "*DEMO* Maze game"){kind=icon}
 "Spin The Black Circle"){kind=icon}
 "Mike Shadow: I paid for it!"){kind=icon}
 "Where Is My Left Sock?"){kind=icon}
yes sir, we'll change that