Hello, there is a problem on the engine if you put transparent textures, then the game will not be displayed on the floor , not the wall , not the bottom and top is not displayed
this is a known issue.
try using custom modifiers and place them on the transparent textures.
i managed to get a transparent textured fence to work using modifiers
also: mad props to you for using my hand in your test game. it is a hand that i am very fond of, it has been been my.... right hand man..... for 38 years now. gotta hand it to ya.