To know who went on yo scratch game do this

when green flag clicked
change [[scratchblocks]
 v] by (0)[/scratchblocks]
add [] to [list v]

Do this

when green flag clicked

change [ Tv ] by (1)
add [username] to [username]
[]

They don't work, since lists and variables cannot store data after someone has exited the project, and other users can not see changes with just global variables/lists.

You can use 2 methods that both use cloud data-
•Saving usernames in a cloud list
•Change a cloud variable so the user appears in cloud history.