This is a very simple mod that adds one thing, a timed pop-up reminder. I'm sure everyone has experienced sitting down to play some Factorio for an hour or two and then suddenly 13 hours have passed, so this mod adds a reminder that will come up every once in a while to tell you how long your session has been so far. You can even set how long to wait for a reminder whenever you load a save file.

NOTE: This mod is singleplayer only, at least for the time being.