Glad you enjoyed it! I also ended up allowing chains on regular matches too (it seemed unsatisfying, for example, to land next to a bunch of 3s but only be able to break one -- especially if you had "setup" those 3s in advance.
I'm working on some ways to balance the difficulty. I hadn't thought about the size of blocks, but I'll probably start spawning higher value blocks at the bottom every few turns to make it harder to keep an empty board.