V2.51 Adding physical phenomena and mathematics into it for close the reality. v2.6.1 (1)Upgrading user interface. (2)Revising user interface for fitting different phones. (3)Adding computer vision to control the bat. (4)Fixing a bug => Sometimes the hit ball was not moving. v2.6.2 (1)Update many items. (2)Debug v2.6.3=>some corrections v2.7.0=> (1)Update challenge items (2)Add VR(virtual reality) mode v2.7.1=>upgrade to support Android 13 v2.7.2=>Adjusting the criteria for passing levels