MTG

I love Maze of Ith. One other trick that I learned when I started playing Lands is that there’s still an opportunity to untap your own creature after damage has been dealt as it’s still technically “attacking”:

You can activate Maze of Ith's ability targeting an attacking creature you control during the combat damage step or the end of combat step, even though it will already have dealt combat damage. This will untap the creature. The damage it dealt will be unaffected.

I used this to untap my own Marit Lage token so it can block in my opponent’s turn.

Maze of Ith doesn't block or remove from combat, it just stops combat damage, so as I understand it, sneak works as he is unblocked (presuming they didn't also block him, of course.), the combat damage based ability does not as damage was prevented.

Yes, you can use Maze on Sneak and Ninjutsu creatures after they enter and prevent them from doing combat damage that turn.

Yes you can use Maze of Ith against sneak or ninjitsu etc. The replacement creature enters attacking so it's a valid target. You also do have an opportunity to respond after the sneak effect resolves but before combat moves to the damage phase.