i noticed some games, the floor level fell below the cubes and walls. i couldn't play mini golf at all due to the floor level was too low and my golf stick couldn't reach the ball. 

however, castle defender and snake master are working fine. 

is there any fix? 

thank you

great! your suggession worked. first i enable the guardian and start drawing the guardian larger than the size of the VR playarea. after finished creating all the walls and object cubes, i disabled the guardian back again. 

thanks!