Add CheckPoints, Good but hard
The game itself is good, i thought it was pretty easy untill the tunnel level.
The game goes from easy to insane in the space of 1 level it really throws you off and there is a major amount of frustration at first and even if you try to time your jump the turret shoots up so the next time you try and jump your dodging a mid air shot as well as trying not to land on a following shot. The only possible ways i can see to making it slightly easier is to increase the delays between shots slightly or increase the tunnel width so you can move around a little when jumping.
Another thing that would help in the tunnel level and actually in all the levels is a little checkpoint so you dont have to start again right from the start, this feature would be slightly useless in the starting levels but as the game goes on it would really ease the frustration and make the game more bearable and fun rather than just being annoying to the point of quitting...
That being said the tunnel level is not impossible its just really hard compared to any level before it, jumping at the start will give you some time to sprint forward for about one or two shots then you have to time your jumps and move mid air so you land just after a shot giving you time to jump again, after that you can run for the space of 1-2 shots that will be mid air and repeat, its frustrating its hard and i didn't feel much of a rewarding feeling after.
The game itself is well made, everything works and nothing really lags so i will give you 8/10 and 4/5 because it is fun at first, its well made, the music is not overly annoying, the controls work well, you only lose 2 stars on the no checkpoints and difficulty curve and i will be looking forward to skill archer 2 if you intend to make one.
Keep it up...