Datapack is compatible with versions 1.20.5 and newer, to play with older version use the alternative download.
This datapack adds a simple timer to Minecraft, which you can use in your minigame or event. Here's how to use the datapack:

• /function timer:show: Toggles visibility of the timer.
• /scoreboard players set Timer IsVisible 0/1: Shows or hides the timer.

• /function timer:play: Toggles the countdown.
• /scoreboard players set Timer IsRunning 0/1: Starts or stops the countdown.

• /function timer:reset: Sets the timer to 1 hour.

If you want to set the timer to another value, use the following commands:

• /scoreboard players set Timer hour [​number]
• /scoreboard players set Timer min [​number]
• /scoreboard players set Timer sec [​number]

You can overwrite the file of a reset function to set the timer to a different value or create multiple preset functions to make the datapack more pleasant to use.

I hope this datapack will be helpful to you,
Duchacek