Update #21Came back from GDC China 2015 in Shanghai:

I've got tons of feedback on the game! I even surveyed some people played the game. Things to wrap up:
Aesthetics:Many people found the game appealing. It reminds them Adventure Island and Super Mario (and even Zelda because some people think Bow looks like Link

. I'm glad to see that retro games are well-received in China, and according to the survey, ~50% players are willing to pay $10 or more for the game when released (yeah, pixel-art are not just cheap art!

).
Dynamics & Humor:Comparing to other action games in the exhibition, our game is a bit "plain" in dynamics. I've added puffing effect, freeze-on-hit and knock-back effect etc. to the game before I went to Shanghai, but we still need to add more effects.
Most Chinese players don't read the dialogues so they don't get the humor we put into the game. That makes me think, we should use graphics to express humor rather than texts, because 1) it's easier to understand 2) it goes better with the gameplay as players don't want to read when dangers could come out at all time.
Gameplay:There are actually two different types of gameplay in our game. The first type is controlling 3 heroes simultaneously using keyboard + mouse. It's the one we've been using since the first version. Another type is using a gamepad to control only one hero, while the other heroes are controlled by other players or AI. It's something we added in v0.5.6.
The biggest issue for the first type of gameplay is the players have to understand the mouse-focus mechanics. Once they get used to the control, they will find joy in the challenges. But the problem is, more than 50% of the players didn't reach that phase, and many of them thought the mechanics was a bug.
The second type is less challenging for single player, because it only requires 1/3 effort to control. But it was very interesting to see that, when it came to Level 2-2 and 3 players started playing co-op (3 heroes in 3 different lanes), tons of sparks of joy came out. It's definitely something we want to keep.