[@Polybius][@Flagg]
If 3 hours straight is too much it can be cut down to 90 minutes (Assuming 30 minute turns).  I am much more concerned about the synchronization of all players than when the time we play is.

As for difficulty as someone who just picked this up the game seems pretty simple to learn compared to some other rule books i've seen out there.  Or perhaps I am saying that due to the lack of number stats involved.  Translating it to a forum medium is what the main challenge will be.  But I don't see that as a impossibility.

On a forum Microscope could play out like this for each pass:

Post 1: The current Lens picks the Focus (which is a Period or Event)
Post 2-5: Other players build on said focus.  The general pattern is if the focus picked a period, everyone makes events, if the focus picked a event, everyone makes scenes.
Post 6: Lens makes last event/scene (Which has to be within the Period or Event the focus him/herself has made)
Post 7: A legacy is made by the player who was lens last. (a legacy is essentially the consequences of an event)
Post 8: A new lens selected. (The next player becomes the new Lens)
Post 9: The new lens picks the Focus.
Etc.

If player 2 is lens, player 3 will be the next lens while player 1 makes the legacy.

The player order as mentioned before is defined by order of interest.  On the first turn for instance, I would be the lens while Polybius would make the legacy and Flagg would be the next lens. (assuming only 3 players).

Pushes can be handled on OOC or in Discord.