How to make "Guess the Giberish"

you can use behavior script to enable a script when start recording

first add new object 
then in resources panel add a script by pressing plus button type script

click on the project and drag the script to Inspector panel

in Object panel click the plus ( + ) button and type behavior then select it
when the script selected you can edit it like in the picture below

make sure to add in object linked in the script to  target to be enable when lens start recording

now with the scripting code
to start a function or stop by time  it you need to use a delay
you can repeat this code once for start a function and other for stoping it

// -----JS CODE-----
// Wait for 2 seconds before executing a function
var delayedEvent = script.createEvent("DelayedCallbackEvent");
delayedEvent.bind(function(eventData)
{
print("delay is over");
});
delayedEvent.reset(2);
print("delay has started");

replace  print("delay is over"); with the randomize code you can find it in think tutorial so you will understand it better than copy paste

https://www.youtube.com/watch?v=9zc2BaMkpeE

if you need any help let us know
Cheers