[Suicide Junkie]

All of the text is set in one of the scenario text files...

I copied a few of the event images to help fill out the briefing Messages.

PS:
If the player saves and then reloads the game, they will not see any future tutorial Messages.

For example, in Exodus, if you play straight through the first 30 turns in one sitting, you'll get countdown warnings as to the star's state before it blows.
Once you've saved and reloaded, then you stop getting the countdown.