pretty good i guess for your first game, here are some suggestions.
1: Make it so that you can travel through worlds, like smash bros. adventure mode
2: Make the guy stand in only one direction, not turning araound
3: Make it so that you can move the spear up and down.
4: Make when you hit the heads, they explode, not dissappear
5: Make power ups, and a certain number of heads that can fall before you lose
6: Make things that if you hit them you lose points
7: Make it if you get hit, you lose points.
8: Make different thing worth different points, for example, slow, large heads are twenty points, and small fast heads are 50 points.
If you need any help with flash games, PM me, I might know what to do.