Nice twist on mahjong! I liked searching for the two connecting pieces, though all of them being letters made it a little unpleasant on the eyes. Could've used different colors for each letter-hex maybe? Though I get you probably wanted to avoid influencing the art style for part 2. The mechanic itself is fun though!
The pieces drawing lines in every direction to find each other was an interesting mechanic, but I wish it was a bit faster.
The game seems quite easy - I tried to play it in three different styles (first an "optimized" style, then choosing only the nearest matching pieces, then just starting in a corner and going from there) - didn't lose once. I don't have a problem with it though because it would be pretty frustrating to clear most of the board only to found out you made a mistake way back and can't beat it.
I played mostly the windows version, but tested the online version - it took about 5 minutes to load, and seemed to be stuck near the end of the loading forever, but worked after that.
When you go back to the main menu, the level music keeps playing on top of the menu music.
(PS. These are probably horrible suggestions, but due to similarity to mahjong you could've named the game "Hexjong", "Mahhex" or "MahJoe" :P)