It's fun and polished, nice work. I enjoyed it more than I expected. I had a few satisfying moments where a big chain reaction would go off. I think that's really the key moment of the game. And it probably happened not quite enough. I'd consider adding a little more "chaos" when two emojis merge, like making the merge cause a proportional force wave that jitters things around a bit. The bigger the emoji you create, the more jitter. That way, I think you'd create more of those "cascade" moments. As it stands, the emoji structure feels just a tiny bit too static as it starts getting full.