Newcomer - 2019. Winter.

Well, I don't know. Mirror Jebus is generally problem-free to understand, IMHO. The road to the center, from the center two mirror passages to the opponent.
On h3dm1 it's harder, but in principle you can still figure it out, and it's intuitively clear which area on the opponent's plane you've emerged into.
But figuring out all the intricacies of the zones on 8xm12 with an abundance of one-way passages, a bunch of roads through a bunch of zones, half (if not more) of which don't even have towns, with the presence of four-way passages and unrealistically long roads — that's scarier to me than electrodynamics was at university.
Although this is my opinion, and it naturally doesn't claim to be authoritative.

Added after 8 minutes
And I also wanted to clarify one point.
By mutual agreement, is it possible to extend the OH?

Regarding Mirror Jebus, I disagree; even experienced players still ask during the game: how many zones are there in the center?
Regarding the OH, by mutual agreement do whatever you want, just don't later make claims against each other and the judges, who won't be able to help you when the OH gets interrupted at the most interesting moment.
Until changes to the rules regarding the OH are made, you can refer to this post: /topic/at/1145279/

3.8 In the event of an OH interruption, the blue player will need to redo the last turn. In this case, it is not necessary to repeat the actions that were performed before the interruption.

3.9. In the event of a crash or disconnect during the OH action, the following should be done:
— If the red player has saved games from the current turn, he should load the most recent one. After that, red continues the turn and finishes it. Blue will be forced to replay the current turn. The simultaneous turn will resume from the next day.
— If the red player does not have saved games from the current turn, then blue should load the last autosave. In this case, both players will have to replay the last turn. The simultaneous turn will begin immediately after loading the autosave and passing the turn from blue.
— In any case, when loading a save, players must replicate their moves as accurately as possible up to the moment of the disconnect.
— Please note: during a simultaneous turn, blue cannot save the game. The only saved games that appear for blue are the autosaves created each turn after combining the results of the players' moves. Red can save the game normally, but blue's position in his saves will always correspond to the start of the turn. Thus, blue's actions are saved only after the turn is completed by both players, before the start of the next turn.