You can use the in-game timer (found in map options)
Or…
You can have 3 properties: hours, minutes, and seconds and set all of those to number properties
You can let the counters update the properties, and then place down a game overlay
Make a block in it that triggers when receiving on the channel you use to increment your clock
Set the block code to this:
Set text (or whatever it is): create text with: Get property: hours
: ":"
: Get property: minutes
: ":"
: Get property: seconds
Or you can use this guide:
but make it increment instead of decrement
this was the closest guide so yeah