This is absolutely amazing. I wish Xu the best of luck on leading the team.
While I know Zifei has fluent in both english and chinese, part of me asks how good is Xu at it. Puzzle games are a more difficult and niche genre to sell too. The biggest thing is that the most successful puzzle games do one of three things ((Usually at least 2.))
1) The puzzle has a very unique and different mechanic behind it that serves as a theme through out the whole. Some games that come to mind like this is the Shift Series ((flash game)), Portal series, and Scribblenaughts ((You drew your own solutions.))
2) A unique story element that has a secret amount of depth and symbolism to it.
3) The puzzles are met with a cast of unique, fun, and well developed characters. For this, some games that rush to mind is Catherine and the Portal Series again.
Difficulty is only the same challenge that all puzzle games have. Some are too hard, some are far too easy. However, the biggest trick here is that is the difficulty fun and challenging, or just aggrevating? Some puzzle games can be insanely hard but aren't aggrevating as the mechanics are very clear and concise. The flash game Shift is a great example here. Other puzzle games however, require a certain flawless timing that is more aggrevating than fun...
When I see Xu's new team working on the Pre-Alpha Demo to prepare to determine how well they can make the gameplay I have to ask if they will capture the first part. Will they be able to find a way to create a Unique and innovative mechanic that will make the game stand out. Even if the characters weren't amazing, the portal games would still do well due to how well the puzzles were made around the mechanics presented. Pathea has already shown their ability to come out with games with unique content in Planet Explorers. Because of their track record I'll give Xu the benefit of the doubt and he does seem very confident on what he wants to make which only further encourages me.
The second point is one that is a bit trickier to catch. There are a few puzzle games which do capture this, however outside of some moments of Catherine, I can't think of much for examples. Honestly I find adventure or RPG's tend to catch this better with Shadows of Colossus, Undertale, or Okami capture it better. This is a tough thing for puzzle games capture as it often does rely heavily on the third thing I point out, the story.
The game is going to fall into the realm of 3d Puzzle games. Its clearly going to be story driven. I wonder how will Xu's innovation will be able to sell the story. I believe if there is going to be anything that will let Pathea sell this game well on steam, it will be the story. Puzzle games on team usually sell well due to a good story more than just good mechanics.
On a side note, does this mean we will see another Pathea team making a Mouse Game? Will Zifei be leading us into a mousehole in a few months?