I hate to bring this up but just one thing really small, the arrow when it hits the wall is still there and it slows down the game a little especially when many arrows hit the wall.
I have tried to do it myself but could not.

I know the code has this.

//hit a wall?
if(event_type == event_block)
{
my.skill1 = 1; //remove me
}

but it just doesnt seem to work, is there something else I could try ?