init.lua

minetest.register_chatcommand("eye_low",{
    func = function( name, param )
        local player = minetest.get_player_by_name(name)
        player:set_eye_offset({x=0,y=-10,z=0},{x=0,y=0,z=0})
        player:set_properties({
            visual_size = {x=1, y=0.5}
        })

    end,
})

minetest.register_chatcommand("eye_normal",{
    func = function( name, param )
        local player = minetest.get_player_by_name(name)
        player:set_eye_offset({x=0,y=0,z=0},{x=0,y=0,z=0})
        player:set_properties({
            visual_size = {x=1, y=1}
        })

    end,
})

minetest.register_chatcommand("eye_high",{
    func = function( name, param )
        local player = minetest.get_player_by_name(name)        player:set_eye_offset({x=0,y=10,z=0},{x=0,y=0,z=0})
        player:set_properties({
            visual_size = {x=1, y=1.5}
        })

    end,
})

minetest.register_chatcommand("antigravity",{
    func = function(name, param)
        local player = minetest.get_player_by_name(name)
        player:set_physics_override({
            gravity = -1.0
        })
    end
})

minetest.register_chatcommand("jump",{
    func = function(name, param)
        local player = minetest.get_player_by_name(name)
        player:set_physics_override({
            gravity = 0.001
        })
    end
})

minetest.register_chatcommand("fast",{
    func = function(name, param)
        local player = minetest.get_player_by_name(name)
        player:set_physics_override({
            speed = 10
        })
    end
})

minetest.register_chatcommand("reversed",{
    func = function(name, param)
        local player = minetest.get_player_by_name(name)
        player:set_physics_override({
            speed = -1.0
        })
    end
})

minetest.register_chatcommand("reset",{
    func = function( name, param )
        local player = minetest.get_player_by_name(name)
        player:set_eye_offset({x=0,y=0,z=0},{x=0,y=0,z=0})
        player:set_properties({
            visual_size = {x=1, y=1, z=1}
        })
        player:set_physics_override({
            speed = 1.0
            gravity = 1.0
        })


    end,
})