I've finally noticed the issue and will fix it after the voting ends. its a problem with the jump height actually, I've set the jump height way too low and didn't have enough time to adjust it properly. the mechanics like back hopping is seen in many games like half-life, legend of Zelda.. etc. The main problem is the jump-height. I just looked at the jump-height just to realize the plyer on average only jumps half a block high.